JavaScript常用方法

1. 将数值四舍五入(保留2位小数)后格式化成金额形式

/**
 * 将数值四舍五入(保留2位小数)后格式化成金额形式
 *
 * @param num 数值(Number或者String)
 * @return 金额格式的字符串,如'1,234,567.45'
 * @type String
 */
function formatCurrency(num) {
    num = num.toString().replace(/\$|\,/g,'');
    if(isNaN(num))
        num = "0";
    sign = (num == (num = Math.abs(num)));
    num = Math.floor(num*100+0.50000000001);
    cents = num%100;
    num = Math.floor(num/100).toString();
    if(cents<10)
    cents = "0" + cents;
    for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)
    num = num.substring(0,num.length-(4*i+3))+','+
    num.substring(num.length-(4*i+3));
    return (((sign)?'':'-') + num + '.' + cents);
}

2. 金额转大写

//金额转大写
var digitUppercase = function (n) {
    var fraction = ['角', '分'];
    var digit = [
        '零', '壹', '贰', '叁', '肆',
        '伍', '陆', '柒', '捌', '玖'
    ];
    var unit = [
        ['元', '万', '亿'],
        ['', '拾', '佰', '仟']
    ];
    var head = n < 0 ? '欠' : '';
    n = Math.abs(n);
    var s = '';
    for (var i = 0; i < fraction.length; i++) {
        s += (digit[Math.floor(n * 10 * Math.pow(10, i)) % 10] + fraction[i]).replace(/零./, '');
    }
    s = s || '整';
    n = Math.floor(n);
    for (var i = 0; i < unit[0].length && n > 0; i++) {
        var p = '';
        for (var j = 0; j < unit[1].length && n > 0; j++) {
            p = digit[n % 10] + unit[1][j] + p;
            n = Math.floor(n / 10);
        }
        s = p.replace(/(零.)*零$/, '').replace(/^$/, '零') + unit[0][i] + s;
    }
    return head + s.replace(/(零.)*零元/, '元')
        .replace(/(零.)+/g, '零')
        .replace(/^整$/, '零元整');
};

3. 计算文件大小

// 计算文件大小函数(保留两位小数),Size为字节大小
// size：初始文件大小
function getfilesize(size) {
    if (!size)
        return "";
    var num = 1024.00; //byte

    if (size < num)
        return size + "B";
    if (size < Math.pow(num, 2))
        return (size / num).toFixed(2) + "K"; //kb
    if (size < Math.pow(num, 3))
        return (size / Math.pow(num, 2)).toFixed(2) + "M"; //M
    if (size < Math.pow(num, 4))
        return (size / Math.pow(num, 3)).toFixed(2) + "G"; //G
    return (size / Math.pow(num, 4)).toFixed(2) + "T"; //T
}

4. 获取输入框选中值

<body>
<input type="text" id="dxs" name="name" />
<input type="button" value="获取"  onclick="getSelectedText()">
<script>
	function getSelectedText(){  
	var inputDom =  document.getElementById("dxs");
    if (document.selection) //IE
    { 
        alert(document.selection.createRange().text); 
    }  
    else {  
        alert(inputDom.value.substring(inputDom.selectionStart,  
                inputDom.selectionEnd));  
    }  
}
</script>
</body>

5. 判断对象是不是数组

function isArray(source) {
    return '[object Array]' == Object.prototype.toString.call(source);
};

6. 获取url根路径

//例如  http://12.3.4.5/joey/
function getRootPath() {
    var strFullPath = window.document.location.href;
    var strPath = window.document.location.pathname;
    var pos = strFullPath.indexOf(strPath);
    var prePath = strFullPath.substring(0, pos);
    var postPath = strPath.substring(0, strPath.substr(1).indexOf('/') + 1);
    return (prePath + postPath);
}

7. 获取url指定参数

//strParame为参数名称,url为地址
function request(strParame, url) {
    var args = new Object();
    var query = "";
    if (!url)
        query = unescape(location.search.substring(1)); // Get query string
    else {
        var index = url.indexOf("?");
        query = url.substring(index + 1);
    }
    var pairs = query.split("&"); // Break at ampersand
    for (var i = 0; i < pairs.length; i++) {
        var pos = pairs[i].indexOf('='); // Look for "name=value"
        if (pos == -1) continue; // If not found, skip
        var argname = pairs[i].substring(0, pos); // Extract the name
        var value = pairs[i].substring(pos + 1); // Extract the value
        try {
            value = decodeURIComponent(value); // Decode it, if needed
        }
        catch (e) { }
        args[argname] = value; // Store as a property
    }
    return args[strParame]; // Return the object
}

8. 创建GUID

//补了零的标准的guid格式（当然多了个“guid_”前缀,以及使用“_”代替“-”）。
function CreateGUID() {
    function s4() {
        return Math.floor((1 + Math.random()) * 0x10000)
          .toString(16)
          .substring(1);
    }
    return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
      s4() + '-' + s4() + s4() + s4();
}

9. 判断一个值是否为空

function IsEmpty(value) {
    if (value == undefined) return true;
    if (value == null) return true;
    if (value == "") return true;
    if (value == "00000000-0000-0000-0000-000000000000") return true;
    return false;
}

10. 设置cookie

function setCookie(name, value) {
    var Days = 300; //此 cookie 将被保存 30 天
    var exp = new Date();    //new Date("December 31, 9998");
    exp.setTime(exp.getTime() + Days * 24 * 60 * 60 * 1000);
    document.cookie = name + "=" + escape(value) + ";expires=" + exp.toGMTString();
}

11. 获取cookie

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

12. 删除cookie

function delCookie(name) {
    var exp = new Date();
    exp.setTime(exp.getTime() - 1);
    var cval = getCookie(name);
    if (cval != null)
        document.cookie = name + "=" + cval + ";expires=" + exp.toGMTString();
}

13. 对象数组去重

//对connects进行去重，el.pageSourceId == element.pageSourceId是去重条件
var connects = connects.reduce(function (prev, element) {
    if (!prev.find(el=>(el.pageSourceId == element.pageSourceId))) {
        prev.push(element)
    }
    return prev
}, []);