Javascript で Cookie を読み書き

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これまたよく使うのでメモ。
WebkitITPはスルー

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//read
window.cookieread = function(c) {
    var ret = '';
    var cn = c + '=';
    var allc = document.cookie;
    var pos = allc.indexOf(cn);
    if(pos != -1) {
        var si = pos + cn.length;
        var ei = allc.indexOf(';', si);
        if(ei == -1) {
            ei = allc.length;
        }
        ret = decodeURIComponent(allc.substring(si, ei));
    }
    return ret;
};
//write
window.cookiewrite = function(cn, val, exp, dom) {
    var value = cn + '=' + encodeURIComponent(val) + '; domain=' + dom + '; path=/;';
    if (exp) {
        var d = new Date();
        d.setDate(d.getDate() + exp);
        var expires = d.toUTCString();
        value = value + ' expires=' + expires;
    }
    document.cookie = value;
};

使い方

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//クッキー名, 値, 有効日数(0ならセッション), 有効ドメイン
cookiewrite('hoge', 'foobar', 30, '.kwonline.org');
 
var hoge = cookieread('hoge');
//foobar

これまたES5の構文だ。