兼容低版本 IE 的 JScript 5.5 实现

发表于:2007-06-21来源:作者:点击数: 标签:
IE 5.5 中的 JScript 版本是 5.5 版,它比以前版本的 JScript 中多了如数组的 push、pop、shift、unshift 方法和 encodeURI、decodeURI 等一些重要的函数。而这些增加的内容在目前其他浏览器(如 Moziila/Firefox 和 Opera)上也同样支持。 因此目前 开发 网

   

IE 5.5 中的 JScript 版本是 5.5 版,它比以前版本的 JScript 中多了如数组的 push、pop、shift、unshift 方法和 encodeURI、decodeURI 等一些重要的函数。而这些增加的内容在目前其他浏览器(如 Moziila/Firefox 和 Opera)上也同样支持。

因此目前开发网站一般对于 IE 浏览器只能兼容到 5.5 版,而对于更低版本的 IE(如 IE 5、IE 4 等),则不再去考虑了。虽然这些低版本的 IE 浏览器目前已经不是主流,但如果能够不需要修改现有代码就能够兼容它们的话,倒是也可以考虑。因此我做了这个兼容低版本 IE 的 JScript 5.5 实现。当然它不可能完全兼容 JScript 5.5,但对于最常用的一些方法,都已经实现了。

该库使用非常简单,只需要在网页的 head 部分加入:

<script type="text/javascript" src="iecompat.js"></script>

就可以了。

完全实现的:

  • Array 对象中:
    • push 方法
    • pop 方法
    • shift 方法
    • unshift 方法
    • splice 方法
  • Date 对象中:
    • toDateString 方法
    • toTimeString 方法
    • toLocaleDateString 方法
    • toLocaleTimeString 方法
  • Function 对象中:
    • apply 方法
    • call 方法
  • Global 对象中:
    • undefined 属性
    • encodeURI 方法
    • encodeURIComponent 方法
    • decodeURI 方法
    • decodeURIComponent 方法
  • Number 对象中:
    • toExponential 方法
    • toFixed 方法
    • toPrecision 方法

对于错误处理,IE 5(JScript 5)中已经有了 try…catch 和 throw 语句,因此 decodeURI、decodeURIComponent、toExponential、toFixed、toPrecision、apply 如果出现运行期错误,在 IE 5 上会抛出跟 IE 5.5+ 中一样的错误信息,但是因为 IE 4 没有错误处理语句,如果上述函数出现运行期错误,将会返回 null。注意上面说的运行期错误,不是指上述函数实现中的错误,而是指在这些函数正常工作的情况下应该出现的错误。

其中 Function 的 apply 函数的实现参考了http://www.openjsan.org/doc/a/ad/adamk/Upgrade/0.04/lib/Upgrade/Function/apply.html
这段程序。

不完全实现的:

  • Error 对象
  • Object 对象中:
    • isPrototypeOf 方法
    • hasOwnProperty 方法
    • propertyIsEnumerable 方法
  • String 对象中:
    • toLocaleLowerCase 方法
    • toLocaleUpperCase 方法
    • localeCompare 方法

因为 IE 4 不具备错误处理语句,因此 Error 对象在 IE 4 上并不具备 IE 5 以上 Error 对象应具有的功能,因此它对于 IE 4 的实现只能保证你在访问或创建它时不会出错。

Object 中的 isPrototypeOf、hasOwnProperty 和 propertyIsEnumerable 方法只是做了模拟实现,其返回值并非总是正确。

String 对象中的 toLocaleLowerCase、toLocaleUpperCase 和 localeCompare 方法实际上并没有考虑本地字符集,但在大部分系统上它还是工作正常的。

完全没有实现的:

  • 正则表达式对象中扩充的属性和限定符

.
———————————————–
如果你想测试低版本的 IE 浏览器上的效果,又没有安装低版本的 IE 浏览器,可以使用这个包:ie_all.zip。这里面都是不需要安装的 IE,直接释放压缩包到一个目录下,就可以运行了。如果你是 win9x 系统,可以到这里下载 win9x 版的 standalone IE。

/* iecompat.js
*
* Copyright Ma Bingyao <andot@ujn.edu.cn>
* Version: 1.1
* LastModified: 2006-02-10
* This library is free.  You can redistribute it and/or modify it.
* http://www.coolcode.cn/?p=126
*/
 
/*@clearcase/" target="_blank" >cc_on @*/
 
/*@if (@_jscript_version < 5)
 
function Error(number, description) {
    if (!number) this.number = 0;
    else this.number = number;
    if (!description) this.description = "";
    else this.description = description;
}
 
@end @*/
 
/*@if (@_jscript_version < 5.5)
 
// this return value was not very correct
Object.prototype.isPrototypeOf = function (o) {
    return (this.constructor == o.constructor);
}
 
// this return value was not very correct
Object.prototype.hasOwnProperty = function (proName) {
    return (typeof(eval("this." + proName)) != "undefind");
}
 
Object.prototype.propertyIsEnumerable = function (proName) {
    for (var o in this) {
        if ((proName == o.toString()) &&
           (proName != "propertyIsEnumerable") &&
           (proName != "isPrototypeOf") &&
           (proName != "hasOwnProperty")) return true;
    }
    return false;
}
 
Error.prototype.message = "";
Error.prototype.name = "Error";
 
Date.prototype.toDateString = function () {
    var s = this.toString().split(' ');
    return [s[0], s[1], s[2], s[5]].join(' ');
}
 
Date.prototype.toTimeString = function () {
    var s = this.toString().split(' ');
    return [s[3], s[4]].join(' ');
}
 
Date.prototype.toLocaleDateString = function () {
    return this.toLocaleString().split(' ')[0];
}
 
Date.prototype.toLocaleTimeString = function () {
    return this.toLocaleString().split(' ')[1];
}
 
String.prototype.toLocaleLowerCase = function () {
    return this.toLowerCase();
}
 
String.prototype.toLocaleUpperCase = function () {
    return this.toUpperCase();
}
 
String.prototype.localeCompare = function (str) {
    if (this > str) return 1;
    if (this < str) return -1;
    return 0;
}
 
Number.prototype.toExponential = function (n) {
    function repeat(s, n) {
        var out = "";
        for (var i = 0; i < n; i++) {
            out += s;
        }
        return out;
    }
    if (!n) {
        n = 0;
    }
    else {
        n = parseInt(n);
        if (n < 0 || n > 20) {
            @if (@_jscript_version < 5)
                return null;
            @else
                var e = new Error(-2146823262, "The number of fractional digits is out of range");
                e.name = "RangeError";
                e.message = e.description;
                throw(e);
            @end
        }
    }
    var s, d, e, len;
    s = this.toString().split("e");
    d = parseFloat(s[0]);
    e = 0;
    if (typeof(s[1]) != "undefined") {
        e = parseInt(s[1]);
    }
    s = d.toString().split(".");
    if (typeof(s[1]) != "undefined") {
        e = e - s[1].length;
        d = s[0] + s[1];
        d = d.replace(/^0+/g, "");
        if (d == "") d = "0";
    }
    s = d.toString();
    len = s.length - 1;
    e += len;
    if (len < n) {
        s += repeat("0", n - len);
    }
    else if (len > n) {
        s = Math.round(parseFloat("." + s) * Math.pow(10, n + 1)).toString();
        if ((s.length - 1) > n) {
            e += 1;
            s = Math.round(parseFloat("." + s) * Math.pow(10, n + 1)).toString();
        }
    }
    if (e >= 0) {
        e = "+" + e;
    }
    if (n == 0) {
        return s + "e" + e;
    }
    else {
        return s.substr(0, 1) + "." + s.substr(1) + "e" + e;
    }
}
 
Number.prototype.toFixed = function (n) {
    function repeat(s, n) {
        var out = "";
        for (var i = 0; i < n; i++) {
            out += s;
        }
        return out;
    }
    if (!n) {
        n = 0;
    }
    else {
        n = parseInt(n);
        if (n < 0 || n > 20) {
            @if (@_jscript_version < 5)
                return null;
            @else
                var e = new Error(-2146823262, "The number of fractional digits is out of range");
                e.name = "RangeError";
                e.message = e.description;
                throw(e);
            @end
        }
    }
    var s, d, e, len;
    s = this.toString().split("e");
    d = parseFloat(s[0]);
    e = 0;
    if (typeof(s[1]) != "undefined") {
        e = parseInt(s[1]);
    }
    s = d.toString().split(".");
    if (typeof(s[1]) != "undefined") {
        e = e - s[1].length;
        d = s[0] + s[1];
        d = d.replace(/^0+/g, "");
        if (d == "") d = "0";
    }
    s = d.toString();
    len = s.length - 1;
   
    if (e >= 0) {
        s += repeat("0", e);
        if (n > 0) {
            s += "." + repeat("0", n);
        }
    }
    else if (-e <= n) {
        s = repeat("0", 1 - e - s.length) + s;
        s = s.substr(0, s.length + e) + "." + s.substr(s.length + e) + repeat("0", n + e);
    }
    else {
        s = repeat("0", 1 - e - s.length) + s;
        d = parseFloat(s.substr(0, s.length + e) + "." + s.substr(s.length + e));
        s = Math.round(d * Math.pow(10, n)).toString();
        if (n > 0) {
            s = repeat("0", n - s.length + 1) + s;
            s = s.substr(0, s.length - n) + "." + s.substr(s.length - n);
        }
    }
    return s;
}
 
Number.prototype.toPrecision = function (n) {
    function repeat(s, n) {
        var out = "";
        for (var i = 0; i < n; i++) {
            out += s;
        }
        return out;
    }
    if (typeof(n) == "undefined") {
        return this.toString();
    }
    else {
        n = parseInt(n);
        if (n < 1 || n > 21) {
            @if (@_jscript_version < 5)
                return null;
            @else
                var e = new Error(-2146823262, "The precision is out of range");
                e.name = "RangeError";
                e.message = e.description;
                throw(e);
            @end
        }
    }
    if (this.valueOf() == 0) {
        if (n == 1) return "0";
        return "0." + repeat("0", n - 1);
    }
    var s, d, e, len;
    s = this.toString().split("e");
    d = parseFloat(s[0]);
    e = 0;
    if (typeof(s[1]) != "undefined") {
        e = parseInt(s[1]);
    }
    s = d.toString().split(".");
    if (typeof(s[1]) != "undefined") {
        e = e - s[1].length;
        d = s[0] + s[1];
        d = d.replace(/^0+/g, "");
        if (d == "") d = "0";
    }
    s = d.toString();
    len = s.length;
    d = parseFloat("." + s) * Math.pow(10, n);
    s = Math.round(d).toString();
    if (s.length > parseInt(d).toString().length) {
        e++;
        s = s.slice(0, -1);
    }
    e += len - s.length;
    len = s.length;
    e += len - 1;
 
    if (e < n && e > -7) {
        if ((e < n - 1) && (e > 0)) {
            s = s.substr(0, e + 1) + "." + s.substr(e + 1);
        }
        else if (e <= 0) {
            s = repeat("0", - e) + s;
            s = s.substr(0, 1) + "." + s.substr(1);
        }
    }
    else {
        if (len < n) {
            s += repeat("0", n - len);
        }
        if (e >= 0) {
            e = "+" + e;
        }
        if (n == 1) {
            s += "e" + e;
        }
        else {
            s = s.substr(0, 1) + "." + s.substr(1) + "e" + e;
        }
    }
    return s;
}
 
var undefined;
 
function encodeURI(str) {
    var l = ['%00', '%01', '%02', '%03', '%04', '%05', '%06',
             '%07', '%08', '%09', '%0A', '%0B', '%0C', '%0D',
             '%0E', '%0F', '%10', '%11', '%12', '%13', '%14',
             '%15', '%16', '%17', '%18', '%19', '%1A', '%1B',
             '%1C', '%1D', '%1E', '%1F', '%20', '!', '%22',
             '#', '$', '%25', '&', "'", '(', ')', '*', '+', ',',
             '-', '.', '/', '0', '1', '2', '3', '4', '5', '6',
             '7', '8', '9', ':', ';', '%3C', '=', '%3E', '?',
             '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
             'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',
             'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '%5B', '%5C',
             '%5D', '%5E', '_', '%60', 'a', 'b', 'c', 'd', 'e',
             'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
             'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y',
             'z', '%7B', '%7C', '%7D', '~', '%7F'];
    var out, i, len, c;
 
    out = "";
    len = str.length;
    for(i = 0; i < len; i++) {
        c = str.charCodeAt(i);
        if (c <= 0x007F) {
            out += l[c];
        }
        else if (c > 0x07FF) {
            out += '%' + (0xE0 | ((c >> 12) & 0x0F)).toString(16).toUpperCase();
            out += '%' + (0x80 | ((c >>  6) & 0x3F)).toString(16).toUpperCase();
            out += '%' + (0x80 | ((c >>  0) & 0x3F)).toString(16).toUpperCase();
        }
        else {
            out += '%' + (0xC0 | ((c >>  6) & 0x1F)).toString(16).toUpperCase();
            out += '%' + (0x80 | ((c >>  0) & 0x3F)).toString(16).toUpperCase();
        }
    }
    return out;
}
 
function encodeURIComponent(str) {
    var l = ['%00', '%01', '%02', '%03', '%04', '%05', '%06',
             '%07', '%08', '%09', '%0A', '%0B', '%0C', '%0D',
             '%0E', '%0F', '%10', '%11', '%12', '%13', '%14',
             '%15', '%16', '%17', '%18', '%19', '%1A', '%1B',
             '%1C', '%1D', '%1E', '%1F', '%20', '!', '%22',
             '%23', '%24', '%25', '%26', "'", '(', ')', '*', '%2B', '%2C',
             '-', '.', '%2F', '0', '1', '2', '3', '4', '5', '6',
             '7', '8', '9', '%3A', '%3B', '%3C', '%3D', '%3E', '%3F',
             '%40', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
             'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',
             'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '%5B', '%5C',
             '%5D', '%5E', '_', '%60', 'a', 'b', 'c', 'd', 'e',
             'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
             'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y',
             'z', '%7B', '%7C', '%7D', '~', '%7F'];
    var out, i, len, c;
 
    out = "";
    len = str.length;
    for(i = 0; i < len; i++) {
        c = str.charCodeAt(i);
        if (c <= 0x007F) {
            out += l[c];
        }
        else if (c > 0x07FF) {
            out += '%' + (0xE0 | ((c >> 12) & 0x0F)).toString(16).toUpperCase();
            out += '%' + (0x80 | ((c >>  6) & 0x3F)).toString(16).toUpperCase();
            out += '%' + (0x80 | ((c >>  0) & 0x3F)).toString(16).toUpperCase();
        }
        else {
            out += '%' + (0xC0 | ((c >>  6) & 0x1F)).toString(16).toUpperCase();
            out += '%' + (0x80 | ((c >>  0) & 0x3F)).toString(16).toUpperCase();
        }
    }
    return out;
}
 
function decodeURI(str) {
    function throwerror() {
        @if (@_jscript_version < 5)
            return null;
        @else
            var e = new Error(-2146823263, "The URI to be decoded is not a valid encoding");
            e.name = "URIError";
            e.message = e.description;
            throw(e);
        @end
    }
    function checkcode() {
        var d1, d2;
        d1 = str.charAt(i++);
        d2 = str.charAt(i++);
        if (isNaN(parseInt(d1, 16)) || isNaN(parseInt(d2, 16))) {
            return throwerror();
        }
        return parseInt(d1 + d2, 16);
    }
    function checkutf8() {
        var c = str.charCodeAt(i++);
        if (c == 37) {
            if ((c = checkcode()) == null) return null;
        }
        if ((c >> 6) != 2) {
            return throwerror();
        }
    }
    var out, i, len;
    var c, c2, c3;
 
    out = "";
    len = str.length;
    i = 0;
    while(i < len) {
        c = str.charCodeAt(i++);
        if (c == 37) {
            if ((c = checkcode()) == null) return null;
        }
        else {
            out += String.fromCharCode(c);
            continue;
        }
        switch(c) {
            case 35: case 36: case 38: case 43: case 44: case 47:
            case 58: case 59: case 61: case 63: case 64: {
                if (str.charCodeAt(i - 3) == 37) {
                    out += str.substr(i - 3, 3);
                }
                else {
                    out += str.substr(i - 1, 1);
                }
                break;
            }
            default: {
                switch(c >> 4) {
                    case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: {
                        // 0xxxxxxx
                        out += String.fromCharCode(c);
                        break;
                    }
                    case 12: case 13: {
                        // 110x xxxx   10xx xxxx
                        if ((c2 = checkutf8()) == null) return null;
                        out += String.fromCharCode(((c & 0x1F) << 6) | (c2 & 0x3F));
                        break;
                    }
                    case 14: {
                        // 1110 xxxx  10xx xxxx  10xx xxxx
                        if ((c2 = checkutf8()) == null) return null;
                        if ((c3 = checkutf8()) == null) return null;
                        out += String.fromCharCode(((c & 0x0F) << 12) |
                                    ((char2 & 0x3F) << 6) |
                                    ((char3 & 0x3F) << 0));
                        break;
                    }
                    default: {
                        out += String.fromCharCode(c);
                        file://return throwerror();
                    }
                }
            }
        }
    }
    return out;
}
 
function decodeURIComponent(str) {
    function throwerror() {
        @if (@_jscript_version < 5)
            return null;
        @else
            var e = new Error(-2146823263, "The URI to be decoded is not a valid encoding");
            e.name = "URIError";
            e.message = e.description;
            throw(e);
        @end
    }
    function checkcode() {
        var d1, d2;
        d1 = str.charAt(i++);
        d2 = str.charAt(i++);
        if (isNaN(parseInt(d1, 16)) || isNaN(parseInt(d2, 16))) {
            return throwerror();
        }
        return parseInt(d1 + d2, 16);
    }
    function checkutf8() {
        var c = str.charCodeAt(i++);
        if (c == 37) {
            if ((c = checkcode()) == null) return null;
        }
        if ((c >> 6) != 2) {
            return throwerror();
        }
    }
    var out, i, len;
    var c, c2, c3;
 
    out = "";
    len = str.length;
    i = 0;
    while(i < len) {
        c = str.charCodeAt(i++);
        if (c == 37) {
            if ((c = checkcode()) == null) return null;
        }
        else {
            out += String.fromCharCode(c);
            continue;
        }
        switch(c >> 4) {
            case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: {
                // 0xxxxxxx
                out += String.fromCharCode(c);
                break;
            }
            case 12: case 13: {
                // 110x xxxx   10xx xxxx
                if ((c2 = checkutf8()) == null) return null;
                out += String.fromCharCode(((c & 0x1F) << 6) | (c2 & 0x3F));
                break;
            }
            case 14: {
                // 1110 xxxx  10xx xxxx  10xx xxxx
                if ((c2 = checkutf8()) == null) return null;
                if ((c3 = checkutf8()) == null) return null;
                out += String.fromCharCode(((c & 0x0F) << 12) |
                            ((char2 & 0x3F) << 6) |
                            ((char3 & 0x3F) << 0));
                break;
            }
            default: {
                return throwerror();
            }
        }
    }
    return out;
}
 
Array.prototype.push = function () {
    var curlen = this.length;
    for (var i = 0; i < arguments.length; i++) {
        this[curlen + i] = arguments[i];
    }
    return this.length;
}
 
Array.prototype.pop = function () {
    var returnValue = this[this.length - 1];
    this.length--;
    return returnValue;
}
 
Array.prototype.shift = function () {
    var returnValue = this[0];
    for (var i = 1; i < this.length; i++) {
        this[i - 1] = this[i];
    }
    this.length--;
    return returnValue;
}
 
Array.prototype.unshift = function () {
    var curlen = this.length;
    var arglen = arguments.length;
    for (var i = curlen - 1; i >= 0 ; i--) {
        this[i + arglen] = this[i] ;
    }
    for (var i = 0; i < arglen; i++) {
        this[i] = arguments[i];
    }
    file://return this.length;  // return this value is Gecko/Opera implementation. but IE don't return anything.
}
 
Array.prototype.splice = function () {
    var start = arguments[0];
    var deleteCount = arguments[1];
    var len = arguments.length - 2;
    var returnValue = this.slice(start);
    for (var i = 0; i < len; i++) {
        this[start + i] = arguments[i + 2];
    }
    for (var i = 0; i < returnValue.length - deleteCount; i++) {
        this[start + len + i] = returnValue[deleteCount + i];
    }
    this.length = start + len + returnValue.length - deleteCount;
    returnValue.length = deleteCount;
    return returnValue;
}
 
Function.prototype.apply = function (o, p) {
    var ps = [];
    if (typeof(o) == "undefined") {
        var __$$apply$$__ = this;
        return eval('__$$apply$$__(' + ps.join(', ') + ');');
    }
    if (p) {
        if (typeof(p[0]) == "undefined") {
            @if (@_jscript_version < 5)
                return null;
            @else
                var e = new Error(-2146823260, "Array or arguments object expected");
                e.name = "TypeError";
                e.message = e.description;
                throw(e);
            @end
        }
        for (var i = 0; i < p.length; i++) {
            ps[i] = 'p[' + i + ']';
        }
    }
    if ((typeof(o) == "object") || (typeof(o) == "function")) {
        o.__$$apply$$__ = this;
        var returnValue = eval('o.__$$apply$$__(' + ps.join(', ') + ');');
        o.__$$apply$$__ = null;
        return returnValue;
    }
    else {
        this.__$$apply$$__ = this;
        var returnValue = eval('this.__$$apply$$__(' + ps.join(', ') + ');');
        this.__$$apply$$__ = null;
        return returnValue;
    }
}
 
Function.prototype.call = function (o) {
    var ps = [];
    if (typeof(o) == "undefined") {
        var __$$call$$__ = this;
        return eval('__$$call$$__(' + ps.join(', ') + ');');
    }
    if (arguments.length > 1) {
        for (var i = 1; i < arguments.length; i++) {
            ps[i - 1] = 'arguments[' + i + ']';
        }
    }
    if ((typeof(o) == "object") || (typeof(o) == "function")) {
        o.__$$call$$__ = this;
        var returnValue = eval('o.__$$call$$__(' + ps.join(', ') + ');');
        o.__$$call$$__ = null;
        return returnValue;
    }
    else {
        this.__$$call$$__ = this;
        var returnValue = eval('this.__$$call$$__(' + ps.join(', ') + ');');
        this.__$$call$$__ = null;
        return returnValue;
    }
}
 
@end @*/

原文转自:http://www.ltesting.net