What to use instead of Object.keys()?

Question

I need to find something in Jquery that can work in IE8 as well as real browsers. I'm brand new to Jquery, the following is my code that works in modern browsers:

$('#FIELD_'+office_id).on('change',function(){
    offices = $(this).val();
for(var i=0; i<=Object.keys(southland.address).length;i++){
        if(offices == Object.keys(southland.address)[i]){
            address = southland.address[offices]Object.keys(southland.address[offices])[0]];
        }
    }

where southland.address comes from an external array. This works perfect in Chrome, IE10 and FF, anything I can do for IE8?

Answer 1

To support Object.keys in older browsers, you can use this snippet:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys#Compatibility

if (!Object.keys) {
  Object.keys = (function () {
    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 = [];

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

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

or this polyfill (which includes other shims, as well):

https://github.com/kriskowal/es5-shim/