1  
 2  /**
 3   * Module exports.
 4   */
 5  
 6  module.exports = deprecate;
 7  
 8  /**
 9   * Mark that a method should not be used.
10   * Returns a modified function which warns once by default.
11   *
12   * If `localStorage.noDeprecation = true` is set, then it is a no-op.
13   *
14   * If `localStorage.throwDeprecation = true` is set, then deprecated functions
15   * will throw an Error when invoked.
16   *
17   * If `localStorage.traceDeprecation = true` is set, then deprecated functions
18   * will invoke `console.trace()` instead of `console.error()`.
19   *
20   * @param {Function} fn - the function to deprecate
21   * @param {String} msg - the string to print to the console when `fn` is invoked
22   * @returns {Function} a new "deprecated" version of `fn`
23   * @api public
24   */
25  
26  function deprecate (fn, msg) {
27    if (config('noDeprecation')) {
28      return fn;
29    }
30  
31    var warned = false;
32    function deprecated() {
33      if (!warned) {
34        if (config('throwDeprecation')) {
35          throw new Error(msg);
36        } else if (config('traceDeprecation')) {
37          console.trace(msg);
38        } else {
39          console.warn(msg);
40        }
41        warned = true;
42      }
43      return fn.apply(this, arguments);
44    }
45  
46    return deprecated;
47  }
48  
49  /**
50   * Checks `localStorage` for boolean values for the given `name`.
51   *
52   * @param {String} name
53   * @returns {Boolean}
54   * @api private
55   */
56  
57  function config (name) {
58    // accessing global.localStorage can trigger a DOMException in sandboxed iframes
59    try {
60      if (!global.localStorage) return false;
61    } catch (_) {
62      return false;
63    }
64    var val = global.localStorage[name];
65    if (null == val) return false;
66    return String(val).toLowerCase() === 'true';
67  }