1  var Buffer = require('buffer/').Buffer;
 2  
 3  /**
 4   * This is a polyfill for the static method `isView` of `ArrayBuffer`, which is
 5   * e.g. missing in IE 10.
 6   *
 7   * @api private
 8   */
 9  if (
10      typeof ArrayBuffer !== 'undefined' &&
11      typeof ArrayBuffer.isView === 'undefined'
12  ) {
13      ArrayBuffer.isView = function(arg) {
14          return viewStrings.indexOf(Object.prototype.toString.call(arg)) > -1;
15      };
16  }
17  
18  /**
19   * @api private
20   */
21  var viewStrings = [
22      '[object Int8Array]',
23      '[object Uint8Array]',
24      '[object Uint8ClampedArray]',
25      '[object Int16Array]',
26      '[object Uint16Array]',
27      '[object Int32Array]',
28      '[object Uint32Array]',
29      '[object Float32Array]',
30      '[object Float64Array]',
31      '[object DataView]',
32  ];
33  
34  /**
35   * @api private
36   */
37  function isEmptyData(data) {
38      if (typeof data === 'string') {
39          return data.length === 0;
40      }
41      return data.byteLength === 0;
42  }
43  
44  /**
45   * @api private
46   */
47  function convertToBuffer(data) {
48      if (typeof data === 'string') {
49          data = new Buffer(data, 'utf8');
50      }
51  
52      if (ArrayBuffer.isView(data)) {
53          return new Uint8Array(data.buffer, data.byteOffset, data.byteLength / Uint8Array.BYTES_PER_ELEMENT);
54      }
55  
56      return new Uint8Array(data);
57  }
58  
59  /**
60   * @api private
61   */
62  module.exports = exports = {
63      isEmptyData: isEmptyData,
64      convertToBuffer: convertToBuffer,
65  };