IE8数组filter（）不起作用

I came to know that in IE8 array filter function is not supported. After looking for help on internet I found this - https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/filter

我才知道在IE8中不支持数组过滤功能。在互联网上寻求帮助后我找到了这个 - https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/filter

It suggest that IE8 will work using above code.

它建议IE8将使用上面的代码。

HTML Code:

<body>
<a href="javascript:void(0)" onclick="calculateDiff()">Calculate</a>
</body>

JS Code:

function calculateDiff() {
    var arr1 = new Array(1, 2, 3);
    var arr2 = new Array(3, 4, 5);
    var res = arr1.diff(arr2);

    alert(res);
}


Array.prototype.diff = function(a) {

    if(!Array.prototype.filter) {
        alert("not supported");
        Array.prototype.filter = function(fun) {
            "use strict";

            if(this == null)
                throw new TypeError();

            var t = Object(this);
            var len = t.length >>> 0;
            if(typeof fun != "function")
                throw new TypeError();

            var res = [];
            var thisp = arguments[1];
            for(var i = 0; i < len; i++) {
                if(i in t) {
                    var val = t[i]; // in case fun mutates this
                    if (fun.call(thisp, val, i, t))
                        res.push(val);
                }
            }

            return res;
        };
    }
    else {
        alert("supported");
        return this.filter(function(i) {
            return !(a.indexOf(i) > -1);
        });
    }
}

I have implemented the solution in this fiddle - http://jsfiddle.net/7LFMA/

我已经在这个小提琴中实现了解决方案 - http://jsfiddle.net/7LFMA/

What is wrong in the code? Why doesn't it work ?

代码有什么问题?为什么不起作用?

2 个解决方案

#1

When running diff for the first time, it will only alert "Not Supported", install the filter polyfill but do nothing. It just returns undefined, instead of diffing like it is supposed to do.

第一次运行diff时,它只会提示“不支持”,安装过滤器polyfill但什么都不做。它只返回undefined,而不是像它应该做的那样进行diffing。

Remove the else, or better just move the filter installation outside the diff function - it is not to be a part of it (e.g. in terms of closure, though modern engines will care about this).

删除其他,或者更好的只是将过滤器安装移到diff函数之外 - 它不是它的一部分(例如在闭合方面,尽管现代引擎会关心这一点)。

Also, IE8 does not support the indexOf method, you will need to put this compat shim in as well.

此外,IE8不支持indexOf方法,您还需要将此compat填充。

if (!Array.prototype.indexOf)
    Array.prototype.indexOf = function (searchElement) {…};

if (!Array.prototype.filter)
    Array.prototype.filter = function(fun) {…};

Array.prototype.diff = function(a) {
    return this.filter(function(i) {
        return !(a.indexOf(i) > -1);
    });
};

function calculateDiff() {
    var arr1 = new Array(1, 2, 3);
    var arr2 = new Array(3, 4, 5);
    var res = arr1.diff(arr2);

    alert(res);
}

#2

IE8 does not support indexOf for arrays - you still use it in the code so once you implement filter, it DOES exist and then IE8 will try to use indexOf.

IE8不支持数组的indexOf - 你仍然在代码中使用它,所以一旦你实现过滤器,它就存在然后IE8将尝试使用indexOf。

In your code you do not actually APPLY the filter once you call DIFF but once you do that, you also need to implement indexOf

在您的代码中,一旦调用DIFF,您实际上并不应用过滤器,但是一旦这样做,您还需要实现indexOf

MDN Array indexOf

MDN数组indexOf

#1