大部分的浏览器一个网站只支持保存20个Cookie,超过20个Cookie,旧的Cookie会被最新的Cookie代替。那么如果要有超过20个Cookie要保存只能将Cookie存为数组然后保存到Cookie。JavaScript中数组是无法直接保存为Cookie的(PHP可以),那要将数组转存为字符串,再保存在Cookie中,简单的一维数组我们直接用toString()或者join就可以了:

JavaScript中toString函数方法是返回对象的字符串表示。
使用方法:objectname.toString([radix])
其中objectname是必选项。要得到字符串表示的对象。
radix是可选项。指定将数字值转换为字符串时的进制。

join是其中一个方法。
格式:objArray.join(seperator)
用途:以seperator指定的字符作为分隔符,将数组转换为字符串,当seperator为逗号时,其作用和toString()相同。

如果多维数组,我们就要用JSON了。

JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式。易于人阅读和编写。同时也易于机器解析和生成。它基于JavaScript Programming Language, Standard ECMA-262 3rd Edition – December 1999的一个子集。 JSON采用完全独立于语言的文本格式,但是也使用了类似于C语言家族的习惯(包括C, C++, C#, Java, JavaScript, Perl, Python等)。这些特性使JSON成为理想的数据交换语言。

这里我们使用PHP2JS的函数库来实现,需要 json_decodejson_encode这两个函数,懂PHP的朋友可以理解这两个函数的意思。json_decode 是JSON到数组,json_encode 是数组到JSON。

需要注意的是JavaScript 保存 Cookie 会将一些字符过滤,如:”{” 被过滤为 “{_” 等。所以在获取 Cookie 时要过滤这些字符,不然 json_decode 会出错。

下面简单举例如下:

<script type="text/javascript">
function setCookie(name, value){
	document.cookie = name + "="+ value;
}

function getCookie(name){
	var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
	if(arr != null) return unescape(arr[2]); return '';
}

function savecookie(){
	var dc = {};
	
	dc['a'] = {};
	dc['a']['x'] = 'ax';
	dc['a']['y'] = 'ay';
	dc['a']['z'] = 'az';
	
	dc['b'] = {};
	dc['b']['x'] = 'bx';
	dc['b']['y'] = 'by';
	dc['b']['z'] = 'bz';
	
	var cdc = json_encode(dc);
	setCookie('testcookie', cdc);
}

function clearcookie(){
	setCookie('testcookie', '');
}

function readcookie(){
	var cdc = getCookie('testcookie');
	cdc = cdc.replace(/,_/g, ',');
	cdc = cdc.replace(/{_/g, '{');
	cdc = cdc.replace(/_}/g, '}');

	var dc = json_decode(cdc);
	for(i in dc){
		for(j in dc[i]){
			document.write(i +':'+ j +':'+ dc[i][j] +'<br>');
		}
	}
}

function json_decode(str_json) {
    // Decodes the JSON representation into a PHP value
    //
    // version: 906.1806
    // discuss at: http://phpjs.org/functions/json_decode
    // +      original by: Public Domain (http://www.json.org/json2.js)
    // + reimplemented by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // + improved by: T.J. Leahy
    // *     example 1: json_decode('[\n    "e",\n    {\n    "pluribus": "unum"\n}\n]');
    // *     returns 1: ['e', {pluribus: 'unum'}]
    /*
        http://www.JSON.org/json2.js
        2008-11-19
        Public Domain.
        NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
        See http://www.JSON.org/js.html
    */

    var json = this.window.JSON;
    if (typeof json === 'object' && typeof json.parse === 'function') {
        return json.parse(str_json);
    }

    var cx = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
    var j;
    var text = str_json;

    // Parsing happens in four stages. In the first stage, we replace certain
    // Unicode characters with escape sequences. JavaScript handles many characters
    // incorrectly, either silently deleting them, or treating them as line endings.
    cx.lastIndex = 0;
    if (cx.test(text)) {
        text = text.replace(cx, function (a) {
            return '\\u' +
            ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
        });
    }

    // In the second stage, we run the text against regular expressions that look
    // for non-JSON patterns. We are especially concerned with '()' and 'new'
    // because they can cause invocation, and '=' because it can cause mutation.
    // But just to be safe, we want to reject all unexpected forms.

    // We split the second stage into 4 regexp operations in order to work around
    // crippling inefficiencies in IE's and Safari's regexp engines. First we
    // replace the JSON backslash pairs with '@' (a non-JSON character). Second, we
    // replace all simple value tokens with ']' characters. Third, we delete all
    // open brackets that follow a colon or comma or that begin the text. Finally,
    // we look to see that the remaining characters are only whitespace or ']' or
    // ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.
    if (/^[\],:{}\s]*$/.
        test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '@').
            replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
            replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {

        // In the third stage we use the eval function to compile the text into a
        // JavaScript structure. The '{' operator is subject to a syntactic ambiguity
        // in JavaScript: it can begin a block or an object literal. We wrap the text
        // in parens to eliminate the ambiguity.

        j = eval('(' + text + ')');

        return j;
    }

    // If the text is not JSON parseable, then a SyntaxError is thrown.
    throw new SyntaxError('json_decode');
}

function json_encode(mixed_val) {
    // Returns the JSON representation of a value
    //
    // version: 906.1806
    // discuss at: http://phpjs.org/functions/json_encode
    // +      original by: Public Domain (http://www.json.org/json2.js)
    // + reimplemented by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // + improved by: T.J. Leahy
    // *     example 1: json_encode(['e', {pluribus: 'unum'}]);
    // *     returns 1: '[\n    "e",\n    {\n    "pluribus": "unum"\n}\n]'
    /*
        http://www.JSON.org/json2.js
        2008-11-19
        Public Domain.
        NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
        See http://www.JSON.org/js.html
    */
    var json = this.window.JSON;
    if (typeof json === 'object' && typeof json.stringify === 'function') {
        return json.stringify(mixed_val);
    }

    var value = mixed_val;

    var quote = function (string) {
        var escapable = /[\\\"\u0000-\u001f\u007f-\u009f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
        var meta = {    // table of character substitutions
            '\b': '\\b',
            '\t': '\\t',
            '\n': '\\n',
            '\f': '\\f',
            '\r': '\\r',
            '"' : '\\"',
            '\\': '\\\\'
        };

        escapable.lastIndex = 0;
        return escapable.test(string) ?
        '"' + string.replace(escapable, function (a) {
            var c = meta[a];
            return typeof c === 'string' ? c :
            '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
        }) + '"' :
        '"' + string + '"';
    };

    var str = function(key, holder) {
        var gap = '';
        var indent = '    ';
        var i = 0;          // The loop counter.
        var k = '';          // The member key.
        var v = '';          // The member value.
        var length = 0;
        var mind = gap;
        var partial = [];
        var value = holder[key];

        // If the value has a toJSON method, call it to obtain a replacement value.
        if (value && typeof value === 'object' &&
            typeof value.toJSON === 'function') {
            value = value.toJSON(key);
        }

        // What happens next depends on the value's type.
        switch (typeof value) {
            case 'string':
                return quote(value);

            case 'number':
                // JSON numbers must be finite. Encode non-finite numbers as null.
                return isFinite(value) ? String(value) : 'null';

            case 'boolean':
            case 'null':
                // If the value is a boolean or null, convert it to a string. Note:
                // typeof null does not produce 'null'. The case is included here in
                // the remote chance that this gets fixed someday.

                return String(value);

            case 'object':
                // If the type is 'object', we might be dealing with an object or an array or
                // null.
                // Due to a specification blunder in ECMAScript, typeof null is 'object',
                // so watch out for that case.
                if (!value) {
                    return 'null';
                }

                // Make an array to hold the partial results of stringifying this object value.
                gap += indent;
                partial = [];

                // Is the value an array?
                if (Object.prototype.toString.apply(value) === '[object Array]') {
                    // The value is an array. Stringify every element. Use null as a placeholder
                    // for non-JSON values.

                    length = value.length;
                    for (i = 0; i < length; i += 1) {
                        partial[i] = str(i, value) || 'null';
                    }

                    // Join all of the elements together, separated with commas, and wrap them in
                    // brackets.
                    v = partial.length === 0 ? '[]' :
                    gap ? '[\n' + gap +
                    partial.join(',\n' + gap) + '\n' +
                    mind + ']' :
                    '[' + partial.join(',') + ']';
                    gap = mind;
                    return v;
                }

                // Iterate through all of the keys in the object.
                for (k in value) {
                    if (Object.hasOwnProperty.call(value, k)) {
                        v = str(k, value);
                        if (v) {
                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
                        }
                    }
                }

                // Join all of the member texts together, separated with commas,
                // and wrap them in braces.
                v = partial.length === 0 ? '{}' :
                gap ? '{\n' + gap + partial.join(',\n' + gap) + '\n' +
                mind + '}' : '{' + partial.join(',') + '}';
                gap = mind;
                return v;
        }
    };

    // Make a fake root object containing our value under the key of ''.
    // Return the result of stringifying the value.
    return str('', {
        '': value
    });
}

savecookie();
readcookie();
</script>

还要注意的就是中文问题,可能会乱码,建议将多字节字符及中文等用 base64 编码解码:

<script type="text/javascript">
function base64_decode( data ) {
    // Decodes string using MIME base64 algorithm
    //
    // version: 905.3122
    // discuss at: http://phpjs.org/functions/base64_decode
    // +   original by: Tyler Akins (http://rumkin.com)
    // +   improved by: Thunder.m
    // +      input by: Aman Gupta
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   bugfixed by: Onno Marsman
    // +   bugfixed by: Pellentesque Malesuada
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // -    depends on: utf8_decode
    // *     example 1: base64_decode('S2V2aW4gdmFuIFpvbm5ldmVsZA==');
    // *     returns 1: 'Kevin van Zonneveld'
    // mozilla has this native
    // - but breaks in 2.0.0.12!
    //if (typeof this.window['btoa'] == 'function') {
    //    return btoa(data);
    //}

    var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    var o1, o2, o3, h1, h2, h3, h4, bits, i = 0, ac = 0, dec = "", tmp_arr = [];

    if (!data) {
        return data;
    }

    data += '';

    do {  // unpack four hexets into three octets using index points in b64
        h1 = b64.indexOf(data.charAt(i++));
        h2 = b64.indexOf(data.charAt(i++));
        h3 = b64.indexOf(data.charAt(i++));
        h4 = b64.indexOf(data.charAt(i++));

        bits = h1<<18 | h2<<12 | h3<<6 | h4;

        o1 = bits>>16 & 0xff;
        o2 = bits>>8 & 0xff;
        o3 = bits & 0xff;

        if (h3 == 64) {
            tmp_arr[ac++] = String.fromCharCode(o1);
        } else if (h4 == 64) {
            tmp_arr[ac++] = String.fromCharCode(o1, o2);
        } else {
            tmp_arr[ac++] = String.fromCharCode(o1, o2, o3);
        }
    } while (i < data.length);

    dec = tmp_arr.join('');
    dec = this.utf8_decode(dec);

    return dec;
}

function base64_encode( data ) {
    // Encodes string using MIME base64 algorithm
    //
    // version: 905.2617
    // discuss at: http://phpjs.org/functions/base64_encode
    // +   original by: Tyler Akins (http://rumkin.com)
    // +   improved by: Bayron Guevara
    // +   improved by: Thunder.m
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   bugfixed by: Pellentesque Malesuada
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // -    depends on: utf8_encode
    // *     example 1: base64_encode('Kevin van Zonneveld');
    // *     returns 1: 'S2V2aW4gdmFuIFpvbm5ldmVsZA=='
    // mozilla has this native
    // - but breaks in 2.0.0.12!
    //if (typeof this.window['atob'] == 'function') {
    //    return atob(data);
    //}

    var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    var o1, o2, o3, h1, h2, h3, h4, bits, i = 0, ac = 0, enc="", tmp_arr = [];

    if (!data) {
        return data;
    }

    data = this.utf8_encode(data+'');

    do { // pack three octets into four hexets
        o1 = data.charCodeAt(i++);
        o2 = data.charCodeAt(i++);
        o3 = data.charCodeAt(i++);

        bits = o1<<16 | o2<<8 | o3;

        h1 = bits>>18 & 0x3f;
        h2 = bits>>12 & 0x3f;
        h3 = bits>>6 & 0x3f;
        h4 = bits & 0x3f;

        // use hexets to index into b64, and append result to encoded string
        tmp_arr[ac++] = b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
    } while (i < data.length);

    enc = tmp_arr.join('');

    switch( data.length % 3 ){
        case 1:
            enc = enc.slice(0, -2) + '==';
        break;
        case 2:
            enc = enc.slice(0, -1) + '=';
        break;
    }

    return enc;
}

function utf8_encode ( argString ) {
    // Encodes an ISO-8859-1 string to UTF-8
    //
    // version: 905.1217
    // discuss at: http://phpjs.org/functions/utf8_encode
    // +   original by: Webtoolkit.info (http://www.webtoolkit.info/)
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: sowberry
    // +    tweaked by: Jack
    // +   bugfixed by: Onno Marsman
    // +   improved by: Yves Sucaet
    // +   bugfixed by: Onno Marsman
    // *     example 1: utf8_encode('Kevin van Zonneveld');
    // *     returns 1: 'Kevin van Zonneveld'
    var string = (argString+'').replace(/\r\n/g, "\n").replace(/\r/g, "\n");

    var utftext = "";
    var start, end;
    var stringl = 0;

    start = end = 0;
    stringl = string.length;
    for (var n = 0; n < stringl; n++) {
        var c1 = string.charCodeAt(n);
        var enc = null;

        if (c1 < 128) {
            end++;
        } else if((c1 > 127) && (c1 < 2048)) {
            enc = String.fromCharCode((c1 >> 6) | 192) + String.fromCharCode((c1 & 63) | 128);
        } else {
            enc = String.fromCharCode((c1 >> 12) | 224) + String.fromCharCode(((c1 >> 6) & 63) | 128) + String.fromCharCode((c1 & 63) | 128);
        }
        if (enc !== null) {
            if (end > start) {
                utftext += string.substring(start, end);
            }
            utftext += enc;
            start = end = n+1;
        }
    }

    if (end > start) {
        utftext += string.substring(start, string.length);
    }

    return utftext;
}

function utf8_decode ( str_data ) {
    // Converts a UTF-8 encoded string to ISO-8859-1
    //
    // version: 905.3122
    // discuss at: http://phpjs.org/functions/utf8_decode
    // +   original by: Webtoolkit.info (http://www.webtoolkit.info/)
    // +      input by: Aman Gupta
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Norman "zEh" Fuchs
    // +   bugfixed by: hitwork
    // +   bugfixed by: Onno Marsman
    // +      input by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // *     example 1: utf8_decode('Kevin van Zonneveld');
    // *     returns 1: 'Kevin van Zonneveld'
    var tmp_arr = [], i = 0, ac = 0, c1 = 0, c2 = 0, c3 = 0;

    str_data += '';

    while ( i < str_data.length ) {
        c1 = str_data.charCodeAt(i);
        if (c1 < 128) {
            tmp_arr[ac++] = String.fromCharCode(c1);
            i++;
        } else if ((c1 > 191) && (c1 < 224)) {
            c2 = str_data.charCodeAt(i+1);
            tmp_arr[ac++] = String.fromCharCode(((c1 & 31) << 6) | (c2 & 63));
            i += 2;
        } else {
            c2 = str_data.charCodeAt(i+1);
            c3 = str_data.charCodeAt(i+2);
            tmp_arr[ac++] = String.fromCharCode(((c1 & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
            i += 3;
        }
    }

    return tmp_arr.join('');
}
</script>

base64_decode 依赖 utf8_decode ,base64_encode 依赖 utf8_encode。

PHP2JS是开源项目,是将PHP的部分函数实现到JavaScript。

3 Comments

  • 王炜

    firefox3.0- 有BUG

    function savecookie(){
    var dc = {};

    dc[‘a’] = {};
    dc[‘a’][‘x’] = ‘ax’;
    dc[‘a’][‘y’] = ‘ay’;
    dc[‘a’][‘z’] = ‘az’;

    dc[‘b’] = {};
    dc[‘b’][‘x’] = ‘bx’;
    dc[‘b’][‘y’] = ‘by’;
    dc[‘b’][‘z’] = ‘bz’;

    var cdc = json_encode(dc);
    cdc = cdc.replace(/\n/g, ”); //firefox3.0- 有换行就错了
    setCookie(‘testcookie’, cdc);
    }

    Reply
  • gmq

    感谢你,不过var dc = {};换成var dc = new Array();貌似就不行了,我是菜鸟,请多指教

    Reply
  • 王炜

    不行就还是用var dc = {};

    Reply

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