JavaScript Object.keys()方法替代与IE8的兼容性

Question

我在IE8中测试不支持Object方法时遇到错误.我正在使用Object.keys()

Object.keys(jsoncont).sort(function(a,b){
   return b.localeCompare(a)
 }).forEach(function(key) {
    var val = jsoncont[key];

   /* My code here */
 });
}

IE8支持这种方法有一个很好的解决方法吗？

Answer 1

Mozilla解释了如何在旧版浏览器中填充函数:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys
if (!Object.keys) {
  Object.keys = (function () {
    'use strict';
    var hasOwnProperty = Object.prototype.hasOwnProperty,
        hasDontEnumBug = !({toString: null}).propertyIsEnumerable('toString'),
        dontEnums = [
          'toString',
          'toLocaleString',
          'valueOf',
          'hasOwnProperty',
          'isPrototypeOf',
          'propertyIsEnumerable',
          'constructor'
        ],
        dontEnumsLength = dontEnums.length;

    return function (obj) {
      if (typeof obj !== 'object' && (typeof obj !== 'function' || obj === null)) {
        throw new TypeError('Object.keys called on non-object');
      }

      var result = [], prop, i;

      for (prop in obj) {
        if (hasOwnProperty.call(obj, prop)) {
          result.push(prop);
        }
      }

      if (hasDontEnumBug) {
        for (i = 0; i < dontEnumsLength; i++) {
          if (hasOwnProperty.call(obj, dontEnums[i])) {
            result.push(dontEnums[i]);
          }
        }
      }
      return result;
    };
  }());
}

Answer 2

如果jsoncont是对象，则可以使用for...in

for (var key in jsoncont) {
...
}

或者按照 中的建议this blog post，您可以像这样创建它

if (!Object.keys) Object.keys = function(o) {
  if (o !== Object(o))
    throw new TypeError('Object.keys called on a non-object');
  var k=[],p;
  for (p in o) if (Object.prototype.hasOwnProperty.call(o,p)) k.push(p);
  return k;
}