js 全角与半角互转

///全角空格为12288，半角空格为32
    ///其他字符半角(33-126)与全角(65281-65374)的对应关系是：均相差65248
    //半角转换为全角函数
    function ToDBC(txtstring) {
        var tmp = "";
        for (var i = 0; i < txtstring.length; i++) {
            if (txtstring.charCodeAt(i) == 32) {
                tmp = tmp + String.fromCharCode(12288);
            }
            if (txtstring.charCodeAt(i) < 127) {
                tmp = tmp + String.fromCharCode(txtstring.charCodeAt(i) + 65248);
            }
        }
        return tmp;
    }
    //全角转换为半角函数
    function ToCDB(str) {
        var tmp = "";
        for (var i = 0; i < str.length; i++) {
            if (str.charCodeAt(i) > 65248 && str.charCodeAt(i) < 65375) {
                tmp += String.fromCharCode(str.charCodeAt(i) - 65248);
            }
            else {
                tmp += String.fromCharCode(str.charCodeAt(i));
            }
        }
        return tmp
    }