LayoutTests/ietestcenter/Javascript/TestCases/15.4.4.20-6-8.js

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ES5Harness.registerTest( {
id: "15.4.4.20-6-8",

path: "TestCases/chapter15/15.4/15.4.4/15.4.4.20/15.4.4.20-6-8.js",

description: "Array.prototype.filter returns an empty array if 'length' is 0 (subclassed Array, length overridden with []",

test: function testcase() {
  foo.prototype = new Array(1, 2, 3);
  function foo() {}
  var f = new foo();
  
  f.length = [];
  
  // objects inherit the default valueOf method of the Object object;
  // that simply returns the itself. Since the default valueOf() method
  // does not return a primitive value, ES next tries to convert the object
  // to a number by calling its toString() method and converting the
  // resulting string to a number.
  //
  // The toString( ) method on Array converts the array elements to strings,
  // then returns the result of concatenating these strings, with commas in
  // between. An array with no elements converts to the empty string, which
  // converts to the number 0. If an array has a single element that is a
  // number n, the array converts to a string representation of n, which is
  // then converted back to n itself. If an array contains more than one element,
  // or if its one element is not a number, the array converts to NaN.

  function cb(){}
  var a = f.filter(cb);
  
  if (Array.isArray(a) &&
      a.length === 0) {
    return true;
  }
 },

precondition: function prereq() {
  return fnExists(Array.prototype.filter,Array.isArray);
 }
});