/ docs / executing_scripts.html
executing_scripts.html
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  5    <title>Executing Scripts | Embark</title>
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 37  
 38    <script async defer src="https://buttons.github.io/buttons.js"></script>
 39  
 40  
 41  <script>
 42    !function(root, factory) {
 43      "function" == typeof define && define.amd ? // AMD. Register as an anonymous module unless amdModuleId is set
 44      define([], function() {
 45          return root.svg4everybody = factory();
 46      }) : "object" == typeof module && module.exports ? // Node. Does not work with strict CommonJS, but
 47      // only CommonJS-like environments that support module.exports,
 48      // like Node.
 49      module.exports = factory() : root.svg4everybody = factory();
 50  }(this, function() {
 51      /*! svg4everybody v2.1.9 | github.com/jonathantneal/svg4everybody */
 52      function embed(parent, svg, target) {
 53          // if the target exists
 54          if (target) {
 55              // create a document fragment to hold the contents of the target
 56              var fragment = document.createDocumentFragment(), viewBox = !svg.hasAttribute("viewBox") && target.getAttribute("viewBox");
 57              // conditionally set the viewBox on the svg
 58              viewBox && svg.setAttribute("viewBox", viewBox);
 59              // copy the contents of the clone into the fragment
 60              for (// clone the target
 61              var clone = target.cloneNode(!0); clone.childNodes.length; ) {
 62                  fragment.appendChild(clone.firstChild);
 63              }
 64              // append the fragment into the svg
 65              parent.appendChild(fragment);
 66          }
 67      }
 68      function loadreadystatechange(xhr) {
 69          // listen to changes in the request
 70          xhr.onreadystatechange = function() {
 71              // if the request is ready
 72              if (4 === xhr.readyState) {
 73                  // get the cached html document
 74                  var cachedDocument = xhr._cachedDocument;
 75                  // ensure the cached html document based on the xhr response
 76                  cachedDocument || (cachedDocument = xhr._cachedDocument = document.implementation.createHTMLDocument(""),
 77                  cachedDocument.body.innerHTML = xhr.responseText, xhr._cachedTarget = {}), // clear the xhr embeds list and embed each item
 78                  xhr._embeds.splice(0).map(function(item) {
 79                      // get the cached target
 80                      var target = xhr._cachedTarget[item.id];
 81                      // ensure the cached target
 82                      target || (target = xhr._cachedTarget[item.id] = cachedDocument.getElementById(item.id)),
 83                      // embed the target into the svg
 84                      embed(item.parent, item.svg, target);
 85                  });
 86              }
 87          }, // test the ready state change immediately
 88          xhr.onreadystatechange();
 89      }
 90      function svg4everybody(rawopts) {
 91          function oninterval() {
 92              // while the index exists in the live <use> collection
 93              for (// get the cached <use> index
 94              var index = 0; index < uses.length; ) {
 95                  // get the current <use>
 96                  var use = uses[index], parent = use.parentNode, svg = getSVGAncestor(parent), src = use.getAttribute("xlink:href") || use.getAttribute("href");
 97                  if (!src && opts.attributeName && (src = use.getAttribute(opts.attributeName)),
 98                  svg && src) {
 99                      if (polyfill) {
100                          if (!opts.validate || opts.validate(src, svg, use)) {
101                              // remove the <use> element
102                              parent.removeChild(use);
103                              // parse the src and get the url and id
104                              var srcSplit = src.split("#"), url = srcSplit.shift(), id = srcSplit.join("#");
105                              // if the link is external
106                              if (url.length) {
107                                  // get the cached xhr request
108                                  var xhr = requests[url];
109                                  // ensure the xhr request exists
110                                  xhr || (xhr = requests[url] = new XMLHttpRequest(), xhr.open("GET", url), xhr.send(),
111                                  xhr._embeds = []), // add the svg and id as an item to the xhr embeds list
112                                  xhr._embeds.push({
113                                      parent: parent,
114                                      svg: svg,
115                                      id: id
116                                  }), // prepare the xhr ready state change event
117                                  loadreadystatechange(xhr);
118                              } else {
119                                  // embed the local id into the svg
120                                  embed(parent, svg, document.getElementById(id));
121                              }
122                          } else {
123                              // increase the index when the previous value was not "valid"
124                              ++index, ++numberOfSvgUseElementsToBypass;
125                          }
126                      }
127                  } else {
128                      // increase the index when the previous value was not "valid"
129                      ++index;
130                  }
131              }
132              // continue the interval
133              (!uses.length || uses.length - numberOfSvgUseElementsToBypass > 0) && requestAnimationFrame(oninterval, 67);
134          }
135          var polyfill, opts = Object(rawopts), newerIEUA = /\bTrident\/[567]\b|\bMSIE (?:9|10)\.0\b/, webkitUA = /\bAppleWebKit\/(\d+)\b/, olderEdgeUA = /\bEdge\/12\.(\d+)\b/, edgeUA = /\bEdge\/.(\d+)\b/, inIframe = window.top !== window.self;
136          polyfill = "polyfill" in opts ? opts.polyfill : newerIEUA.test(navigator.userAgent) || (navigator.userAgent.match(olderEdgeUA) || [])[1] < 10547 || (navigator.userAgent.match(webkitUA) || [])[1] < 537 || edgeUA.test(navigator.userAgent) && inIframe;
137          // create xhr requests object
138          var requests = {}, requestAnimationFrame = window.requestAnimationFrame || setTimeout, uses = document.getElementsByTagName("use"), numberOfSvgUseElementsToBypass = 0;
139          // conditionally start the interval if the polyfill is active
140          polyfill && oninterval();
141      }
142      function getSVGAncestor(node) {
143          for (var svg = node; "svg" !== svg.nodeName.toLowerCase() && (svg = svg.parentNode); ) {}
144          return svg;
145      }
146      return svg4everybody;
147  });
148  
149  svg4everybody();
150  </script>
151  </head>
152  
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215        <h1 class="c-title u-text-ghost">Documentation</h1>
216  
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218  
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236              Guides
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245                <div class="">
246                  <h3 class="c-category-title">Getting Started</h3>
247                  <ul class="o-list-bare">
248                    
249                    <li class="o-list-bare__item">
250                      <a href="/docs/overview.html" title="Overview" class="u-link-uniform ">Overview</a>
251                      <!-- <div class="o-distance-m">
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253                          <li class="o-list-bare__item">
254                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
255                          </li>
256                        </ul>
257                      </div> -->
258                    </li>
259                    
260                    <li class="o-list-bare__item">
261                      <a href="/docs/installation.html" title="Installation" class="u-link-uniform ">Installation</a>
262                      <!-- <div class="o-distance-m">
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266                          </li>
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270                    
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286                  <h3 class="c-category-title">General Usage</h3>
287                  <ul class="o-list-bare">
288                    
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290                      <a href="/docs/create_project.html" title="Creating apps" class="u-link-uniform ">Creating apps</a>
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295                          </li>
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297                      </div> -->
298                    </li>
299                    
300                    <li class="o-list-bare__item">
301                      <a href="/docs/structure.html" title="App structure" class="u-link-uniform ">App structure</a>
302                      <!-- <div class="o-distance-m">
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310                    
311                    <li class="o-list-bare__item">
312                      <a href="/docs/running_apps.html" title="Running apps" class="u-link-uniform ">Running apps</a>
313                      <!-- <div class="o-distance-m">
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317                          </li>
318                        </ul>
319                      </div> -->
320                    </li>
321                    
322                    <li class="o-list-bare__item">
323                      <a href="/docs/dashboard.html" title="Using the dashboard" class="u-link-uniform ">Using the dashboard</a>
324                      <!-- <div class="o-distance-m">
325                        <ul class="o-list-bare c-navigation__subnav">
326                          <li class="o-list-bare__item">
327                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
328                          </li>
329                        </ul>
330                      </div> -->
331                    </li>
332                    
333                    <li class="o-list-bare__item">
334                      <a href="/docs/using_the_console.html" title="Using the console" class="u-link-uniform ">Using the console</a>
335                      <!-- <div class="o-distance-m">
336                        <ul class="o-list-bare c-navigation__subnav">
337                          <li class="o-list-bare__item">
338                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
339                          </li>
340                        </ul>
341                      </div> -->
342                    </li>
343                    
344                    <li class="o-list-bare__item">
345                      <a href="/docs/environments.html" title="Environments" class="u-link-uniform ">Environments</a>
346                      <!-- <div class="o-distance-m">
347                        <ul class="o-list-bare c-navigation__subnav">
348                          <li class="o-list-bare__item">
349                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
350                          </li>
351                        </ul>
352                      </div> -->
353                    </li>
354                    
355                    <li class="o-list-bare__item">
356                      <a href="/docs/configuration.html" title="Configuration" class="u-link-uniform ">Configuration</a>
357                      <!-- <div class="o-distance-m">
358                        <ul class="o-list-bare c-navigation__subnav">
359                          <li class="o-list-bare__item">
360                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
361                          </li>
362                        </ul>
363                      </div> -->
364                    </li>
365                    
366                    <li class="o-list-bare__item">
367                      <a href="/docs/pipeline_and_webpack.html" title="Building & Compiling" class="u-link-uniform ">Building & Compiling</a>
368                      <!-- <div class="o-distance-m">
369                        <ul class="o-list-bare c-navigation__subnav">
370                          <li class="o-list-bare__item">
371                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
372                          </li>
373                        </ul>
374                      </div> -->
375                    </li>
376                    
377                    <li class="o-list-bare__item">
378                      <a href="/docs/executing_scripts.html" title="Executing Scripts" class="u-link-uniform is-active">Executing Scripts</a>
379                      <!-- <div class="o-distance-m">
380                        <ul class="o-list-bare c-navigation__subnav">
381                          <li class="o-list-bare__item">
382                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
383                          </li>
384                        </ul>
385                      </div> -->
386                    </li>
387                    
388                    <li class="o-list-bare__item">
389                      <a href="/docs/javascript_usage.html" title="Using EmbarkJS" class="u-link-uniform ">Using EmbarkJS</a>
390                      <!-- <div class="o-distance-m">
391                        <ul class="o-list-bare c-navigation__subnav">
392                          <li class="o-list-bare__item">
393                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
394                          </li>
395                        </ul>
396                      </div> -->
397                    </li>
398                    
399                  </ul>
400                </div>
401              
402                <div class="o-distance-xl">
403                  <h3 class="c-category-title">Smart Contract Development</h3>
404                  <ul class="o-list-bare">
405                    
406                    <li class="o-list-bare__item">
407                      <a href="/docs/contracts_configuration.html" title="Configuration" class="u-link-uniform ">Configuration</a>
408                      <!-- <div class="o-distance-m">
409                        <ul class="o-list-bare c-navigation__subnav">
410                          <li class="o-list-bare__item">
411                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
412                          </li>
413                        </ul>
414                      </div> -->
415                    </li>
416                    
417                    <li class="o-list-bare__item">
418                      <a href="/docs/contracts_deployment.html" title="Accounts & Deployment" class="u-link-uniform ">Accounts & Deployment</a>
419                      <!-- <div class="o-distance-m">
420                        <ul class="o-list-bare c-navigation__subnav">
421                          <li class="o-list-bare__item">
422                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
423                          </li>
424                        </ul>
425                      </div> -->
426                    </li>
427                    
428                    <li class="o-list-bare__item">
429                      <a href="/docs/contracts_imports.html" title="Special Imports" class="u-link-uniform ">Special Imports</a>
430                      <!-- <div class="o-distance-m">
431                        <ul class="o-list-bare c-navigation__subnav">
432                          <li class="o-list-bare__item">
433                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
434                          </li>
435                        </ul>
436                      </div> -->
437                    </li>
438                    
439                    <li class="o-list-bare__item">
440                      <a href="/docs/contracts_testing.html" title="Testing" class="u-link-uniform ">Testing</a>
441                      <!-- <div class="o-distance-m">
442                        <ul class="o-list-bare c-navigation__subnav">
443                          <li class="o-list-bare__item">
444                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
445                          </li>
446                        </ul>
447                      </div> -->
448                    </li>
449                    
450                    <li class="o-list-bare__item">
451                      <a href="/docs/contracts_javascript.html" title="Smart Contracts in JavaScript" class="u-link-uniform ">Smart Contracts in JavaScript</a>
452                      <!-- <div class="o-distance-m">
453                        <ul class="o-list-bare c-navigation__subnav">
454                          <li class="o-list-bare__item">
455                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
456                          </li>
457                        </ul>
458                      </div> -->
459                    </li>
460                    
461                  </ul>
462                </div>
463              
464                <div class="o-distance-xl">
465                  <h3 class="c-category-title">Blockchain Client</h3>
466                  <ul class="o-list-bare">
467                    
468                    <li class="o-list-bare__item">
469                      <a href="/docs/blockchain_configuration.html" title="Configuration" class="u-link-uniform ">Configuration</a>
470                      <!-- <div class="o-distance-m">
471                        <ul class="o-list-bare c-navigation__subnav">
472                          <li class="o-list-bare__item">
473                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
474                          </li>
475                        </ul>
476                      </div> -->
477                    </li>
478                    
479                    <li class="o-list-bare__item">
480                      <a href="/docs/blockchain_accounts_configuration.html" title="Managing Accounts" class="u-link-uniform ">Managing Accounts</a>
481                      <!-- <div class="o-distance-m">
482                        <ul class="o-list-bare c-navigation__subnav">
483                          <li class="o-list-bare__item">
484                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
485                          </li>
486                        </ul>
487                      </div> -->
488                    </li>
489                    
490                  </ul>
491                </div>
492              
493                <div class="o-distance-xl">
494                  <h3 class="c-category-title">Storage (IPFS/Swarm)</h3>
495                  <ul class="o-list-bare">
496                    
497                    <li class="o-list-bare__item">
498                      <a href="/docs/storage_configuration.html" title="Configuration" class="u-link-uniform ">Configuration</a>
499                      <!-- <div class="o-distance-m">
500                        <ul class="o-list-bare c-navigation__subnav">
501                          <li class="o-list-bare__item">
502                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
503                          </li>
504                        </ul>
505                      </div> -->
506                    </li>
507                    
508                    <li class="o-list-bare__item">
509                      <a href="/docs/storage_deployment.html" title="Deploying apps" class="u-link-uniform ">Deploying apps</a>
510                      <!-- <div class="o-distance-m">
511                        <ul class="o-list-bare c-navigation__subnav">
512                          <li class="o-list-bare__item">
513                            <a href="#" title="What is Embark?" class="u-link-uniform">What is Embark?</a>
514                          </li>
515                        </ul>
516                      </div> -->
517                    </li>
518                    
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766          <p class="c-meta">Last updated: February 18th 2020
767            (<a href="https://github.com/embarklabs/embark/edit/master/site/source/docs/executing_scripts.md" target="_blank">
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771          <div class="o-standard-page">
772            <h1>Executing Scripts</h1>
773            <p>There are various features in Embark that help you making the deployment of your DApps and Smart Contracts as smooth as possible. Next to general <a href="contracts_configuration.html">Smart Contract Configurations</a>, <a href="contracts_configuration.html#Deployment-hooks">Deployment Hooks</a> and <a href="cockpit_introduction.html">Cockpit</a>, there’s the possibility to run (migration) scripts as well.</p>
774  <p>In this guide we’ll explore why scripts are useful and how they can be run.</p>
775  <h2 id="Why-scripts"><a href="#Why-scripts" class="headerlink" title="Why scripts?"></a>Why scripts?</h2><p>Given that Embark supports <a href="contracts_configuration.html#afterDeploy-hook">afterDeploy</a> hooks that make it extremely easy to perform custom operations after all of your Smart Contracts have been deployed, you might wonder when and where scripts can be useful.</p>
776  <p>It’s important to note that <code>afterDeploy</code> hooks are executed every time all Smart Contracts have been deployed. Often there are cases where running a (migration) script manually is what you really need.</p>
777  <p>Scripts let you do exactly that as they can be run at any time, regardless of what your app’s current deployment status is.</p>
778  <h2 id="What’s-a-script"><a href="#What’s-a-script" class="headerlink" title="What’s a script?"></a>What’s a script?</h2><p>A script is really just a file with an exported function that has special dependencies injected into it. Here’s what it could look like:</p>
779  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">modules.exports &#x3D; async (&#123; contracts, web3, logger&#125;) &#x3D;&gt; &#123;</span><br><span class="line">  ...</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>
780  
781  <p>The injected parameters are:</p>
782  <ul>
783  <li><code>contracts</code> - A map object containing all of your Smart Contracts as Embark Smart Contract instances.</li>
784  <li><code>web3</code> - A web3 instances to give you access to things like accounts.</li>
785  <li><code>logger</code> - Embark’s custom logger.</li>
786  </ul>
787  <p>Scripts can be located anywhere on your machine, but should most likely live inside your project’s file tree in a dedicated folder.</p>
788  <h2 id="Running-scripts"><a href="#Running-scripts" class="headerlink" title="Running scripts"></a>Running scripts</h2><p>To run a script, use the CLI <code>exec</code> command and specify an environment as well as the script to be executed:</p>
789  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">$ embark exec development scripts&#x2F;001.js</span><br></pre></td></tr></table></figure>
790  
791  <p>The command above will execute the function in <code>scripts/001.js</code> and ensures that Smart Contracts are deployed in the <code>development</code> environment.</p>
792  <p>If you have multiple scripts that should run in order, it’s also possible to specify the directory in which they live in:</p>
793  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">$ embark exec development scripts</span><br></pre></td></tr></table></figure>
794  
795  <p>Embark will then find all script files inside the specified directory (in this case <code>scripts</code>) and then run them one by one. If any of the scripts fails by emitting an error, Embark will abort the execution. Scripts are executed in sequence, which means all following scripts won’t be executed in case of an error.</p>
796  <h2 id="Error-Handling"><a href="#Error-Handling" class="headerlink" title="Error Handling"></a>Error Handling</h2><p>It’s possible and recommended for scripts to emit proper errors in case they fail to do their job. There are several ways to emit an error depending on how you write your function. Scripts are executed asyncronously, so one way to emit an error is to reject a promise:</p>
797  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">modules.exports &#x3D; () &#x3D;&gt; &#123;</span><br><span class="line">  return new Promise((resolve, reject) &#x3D;&gt; &#123;</span><br><span class="line">    reject(new Error(&#39;Whoops, something went wrong&#39;));</span><br><span class="line">  &#125;);</span><br><span class="line">&#125;;</span><br><span class="line"></span><br><span class="line">&#x2F;&#x2F; or</span><br><span class="line">modules.exports &#x3D; () &#x3D;&gt; &#123;</span><br><span class="line">  return Promise.reject(new Error (&#39;Whoops, something went wrong&#39;));</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>
798  
799  <p>If your script uses the <code>async/await</code> syntax, errors are emitted by default when using other <code>async</code> APIs that fail:</p>
800  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">module.exports &#x3D; async () &#x3D;&gt; &#123;</span><br><span class="line">  await someAPIThatFails(); &#x2F;&#x2F; this will emit an error</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>
801  
802  <p>If an error is emitted, Embark will do its best to give you information about the original error:</p>
803  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">  001.js running....</span><br><span class="line">Script &#39;001.js&#39; failed to execute. Original error: Error: Whoops, something went wrong</span><br></pre></td></tr></table></figure>
804  
805  <h2 id="Tracking-scripts"><a href="#Tracking-scripts" class="headerlink" title="Tracking scripts"></a>Tracking scripts</h2><p>Just like Smart Contract deployments are tracked, (migration) scripts can be tracked as well. Since scripts can be one-off operations, Embark will not track whether they have been executed by default. Users are always able to run a script using the <code>exec</code> command as discussed in the previous sections.</p>
806  <p>To have Embark “remember” that a certain script was already run, you can use the <code>--track</code> option of the <code>exec</code> command, which will force tracking for this particular script:</p>
807  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">$ embark exec development scripts&#x2F;001.js --track</span><br></pre></td></tr></table></figure>
808  
809  <p>If we try to run the script again with the <code>--track</code> option, Embark will notice that the script has already been executed and tell us that it’s “already done”.</p>
810  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">$ embark exec development scripts&#x2F;001.js --track</span><br><span class="line">.. 001.js already done</span><br></pre></td></tr></table></figure>
811  
812  <p>If however, we don’t provide the <code>--track</code> flag, Embark will execute the script as usual.</p>
813  <p>For cases in which we <strong>do</strong> want to track a set of scripts, especially when the main use case are migration operations, we can put our scripts in a special “migrations” directory. All scripts inside that directory will be tracked by default.</p>
814  <p>The directory can be specified using the <code>migrations</code> property in your project’s embark.json:</p>
815  <figure class="highlight plain"><table><tr><td class="code"><pre><span class="line">&#123;</span><br><span class="line">  ...</span><br><span class="line">  migrations: &#39;migrations&#39;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
816  
817  <p>If no such property is specified, Embark will default to “migrations”. Running any script or set of scripts is then automatically tracked.</p>
818  
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839          <ol class="o-list-bare"><li class="o-list-bare__item o-list-bare-level-2 o-ellipsis"><a href="#Why-scripts" class="u-link-uniform">Why scripts?</a></li><li class="o-list-bare__item o-list-bare-level-2 o-ellipsis"><a href="#What’s-a-script" class="u-link-uniform">What’s a script?</a></li><li class="o-list-bare__item o-list-bare-level-2 o-ellipsis"><a href="#Running-scripts" class="u-link-uniform">Running scripts</a></li><li class="o-list-bare__item o-list-bare-level-2 o-ellipsis"><a href="#Error-Handling" class="u-link-uniform">Error Handling</a></li><li class="o-list-bare__item o-list-bare-level-2 o-ellipsis"><a href="#Tracking-scripts" class="u-link-uniform">Tracking scripts</a></li></ol>
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