常用js方法集合，动态加载js方法--判断变量是否为空--截取小数点后几位--截取带中文的字条串

/*
 * 动态加载外部js文件
 */
loadJS: function(url,id){
        if(typeof(id)=='undefined'){
            id = new Date().getTime();
        }
        var scriptTag = document.getElementById( id );
        var oHead = document.getElementsByTagName('HEAD').item(0);
        var oScript= document.createElement("script");
        if ( scriptTag  ) oHead.removeChild( scriptTag  );
        oScript.id = id;
        oScript.type = "text/javascript";
        oScript.src=url ;
        oHead.appendChild( oScript);
    }

// 初始化QQ聊天
    initQQDailog: function (qq) {
        var html = "<a target=\"_blank\" href=\"http://wpa.qq.com/msgrd?v=3&uin=" + qq + "&site=qq&menu=yes\">" +
            "<img border=\"0\" src=\"http://wpa.qq.com/pa?p=2:" + qq + ":52&v=" + new Date().getTime() + "\" alt=\"点击这里给我发消息\" title=\"点击这里给我发消息\"/>" +
            "</a>";
        return html;
    }

/*
 * 判断值是否为空
 **/
isEmpty: function (obj) {
        if (obj == '' || obj == null || obj == undefined) {
            return true;
        }

        if (typeof(obj) == 'object') {
            for (var key in obj) {
                return false;
            }
            return true;
        }

        return false;
    }

/*
 * 拼接对象
 */
concatObj: function () {
        var output = {};
        for (var i in arguments) {
            for (var key in arguments[i]) {
                output[key] = arguments[i][key];
            }
        }
        return output;
    }

/*
 * 把对象转换成url参数
 */
obj2Para: function (obj) {
        var para = "";
        $.each(obj, function (i, v) {
            para += "&" + i + "=" + v;
        });
        return para.substr(1);
    }

/*
 * js进行模版替换
 */
fetchView: function(strView,objData){
        var matches = strView.match(/<!--\$\w+-->/g);
        if(matches != null){
            matches.forEach(function(v){
                var key = String(v.match(/\w+/));
                strView = strView.replace(v,objData[key]);
            });
        }

        var matches = strView.match(/\{\$\w+\}/g);
        if(matches != null){
            matches.forEach(function(v){
                var key = String(v.match(/\w+/));
                strView = strView.replace(v,objData[key]);
            });
        }

        return strView;
    }

chkEmail: function(strEmail) {
        if (!/^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/.test(strEmail)) {
            return false;
        } else {
            return true;
        }
    }

/*
 * 截取小数点后几位
 */
subNumber : function(number, digit){
    var digit = digit || 2;
    var numberStr = number.toString();
    var index = numberStr.indexOf(".");
    if(index == -1){
        return numberStr;
    }else{
        return numberStr.substring(0, index + digit + 1);
    }
}

/*
 * 截取带中文的字条串 utf-8
 */
sub_str : function (str, len) {
    var strlen = 0;
    var s = "";
    for (var i = 0; i < str.length; i++) {
        if (str.charCodeAt(i) > 128) {
            strlen += 2;
        } else {
            strlen++;
        }
        s += str.charAt(i);
        if (strlen >= len) {
            return s + '…';
        }
    }
    return s;
}

/*
 * 按住shift选择一个范围内的checkbox
 */
shiftPitch: function(pMark){
    var runthis = this;
    runthis.checkBoxObj = '';
    runthis.shiftDown = false;
    runthis.num = 1;
    //checkbox初始化
    $('body').find(pMark+' tbody input[type=checkbox]').each(function(){
        $(this).data('num',runthis.num++);
    });

    //checkbox选中事件
    $('body').find(pMark+' input[type=checkbox]:checkbox').change(function(){
        if($(this).parent().parent().parent().find('input:checkbox:checked').length>0){
            $(this).parent().parent().parent().siblings('thead').find('input[type=checkbox]').attr('checked',true);
        }else if($(this).parent().parent().parent().find('input:checkbox:checked').length<=0){
            $(this).parent().parent().parent().siblings('thead').find('input[type=checkbox]').attr('checked',false);
        }
        if($(this).is(':checkbox:checked') && typeof(runthis.checkBoxObj) == 'object' && runthis.shiftDown == true){
            var oldNum = parseInt(runthis.checkBoxObj.data('num'));
            var runNum = parseInt($(this).data('num'));
            var small = oldNum>runNum?runNum:oldNum;
            var big = oldNum>runNum?oldNum:runNum;
            $(this).parents(pMark).find('tbody input[type=checkbox]').each(function(){
                if(parseInt($(this).data('num'))>=small && parseInt($(this).data('num'))<=big){
                    $(this).attr('checked',true);
                    $(this).parents('tr').addClass('selected');
                }
            });
        }
        runthis.checkBoxObj = $(this);

    })