一些有用的工具函数，如input输入小数的位数限制

/**
 * 限制数字且最多输入小数的位数
 * @param  {[type]} elem 输入的对象
 * @param  {[type]} len  输入长度
 * @return {[type]}      [description]
 */
function limitNumber(elem, len) {
    elem.addEventListener("input",function(e){
        var result = "";
        var val = e.target.value;
        //最后一个字符是.
        if (val[val.length - 1] === ".") {
            //如果.符号超过一个
            if (val.split(".").length > 2) {
                val = val.slice(0, -1);
            } else if (val.split(".").length === 2 && val.slice(val.indexOf("."), val.length - 1).length > 2) {
                val = val.slice(0, val.indexOf(".") + 2)
            }
        }
        //存在.符号并且不止一位数
        else if (val[val.length - 1] !== "." && val.indexOf(".") !== -1) {
            val = val.slice(0, val.indexOf(".") + (len || 2 + 1))
        }
        e.target.value = val.replace(/[^\d\.]/g, "");
    })
}

注：在调用的时候需要用原生来绑定对象

日期转换函数，可以根据需求来设置前几天后几天

Date.prototype.format = function(pattern) {
    function zeroize(num) {
        return num < 10 ? "0" + num : num;
    };
    var pattern = pattern; //    YYYY-MM-DD 或 MM-DD-YYYY 或 YYYY-MM-DD , hh : mm : ss
    var dateObj = {
        "Y": this.getFullYear(),
        "M": zeroize(this.getMonth() + 1),
        "D": zeroize(this.getDate()),
        "h": zeroize(this.getHours()),
        "m": zeroize(this.getMinutes()),
        "s": zeroize(this.getSeconds())
    };
    return pattern.replace(/YYYY|MM|DD|hh|mm|ss/g, function(match) {
        switch (match) {
            case "YYYY":
                return dateObj.Y;
            case "MM":
                return dateObj.M;
            case "DD":
                return dateObj.D;
            case "hh":
                return dateObj.h;
            case "mm":
                return dateObj.m;
            case "ss":
                return dateObj.s;
        };
    });
};
Date.prototype.past = function(pattern, pastDays) {
    function zeroize(num) {
        return num < 10 ? "0" + num : num;
    };
    var pastday = new Date((this - 0) - 1000 * 60 * 60 * 24 * pastDays);
    var pattern = pattern; //    YYYY-MM-DD 或 MM-DD-YYYY 或 YYYY-MM-DD , hh : mm : ss
    var dateObj = {
        "Y": pastday.getFullYear(),
        "M": zeroize(pastday.getMonth() + 1),
        "D": zeroize(pastday.getDate()),
        "h": zeroize(pastday.getHours()),
        "m": zeroize(pastday.getMinutes()),
        "s": zeroize(pastday.getSeconds())
    };
    return pattern.replace(/YYYY|MM|DD|hh|mm|ss/g, function(match) {
        switch (match) {
            case "YYYY":
                return dateObj.Y;
            case "MM":
                return dateObj.M;
            case "DD":
                return dateObj.D;
            case "hh":
                return dateObj.h;
            case "mm":
                return dateObj.m;
            case "ss":
                return dateObj.s;
        };
    });
};
Date.prototype.yestoday = function(pattern) {
    return this.past(pattern, 1);
};
Date.prototype.tomorrow = function(pattern) {
    return this.past(pattern, -1);
};

单位自动转换

function getKit(array,radix,units){
        var result = [];

        //单位转换
        function getUnit(array){
            var temp = {};
            var unit = ['byte','KB','MB','GB','TB'];

            //存储所有配置单位的最大值
            function max(){
                var str=[];
                for(var i=1;i<unit.length+1;i++){
                    var arr = Math.pow(radix,i);
                    str.push(arr);
                }
                return str;
            };
            //计算索引
            var index = max();
            for(var i=0;i<index.length;i++){
                if(index[i] > array ){
                    temp.num=(array / Math.pow(radix,i)).toFixed(2),
                    temp.unit = unit[i];
                    break;
                }
            }
            return temp;
        }
        for(var i=0;i<array.length;i++){
            result.push(getUnit(array[i]));
        }
        return result;
    }