javascript 实用函数

1.去除字符串空格

/*去左空格*/
function ltrim(s) {
    return s.replace(/^(\s*|　*)/, "");
}

/*去右空格*/
function rtrim(s) {
    return s.replace(/(\s*|　*)$/, "");
}

/*去左右空格*/
function trim(s) {
    return ltrim(rtrim(s));
}

2.获取url地址栏参数

function getUrlQueryParam(name) {
    var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");
    var r = window.location.search.substr(1).match(reg);
    var value = ‘‘;
    if (r != null) {
        value = decodeURIComponent(r[2]);
    }
    return value;
}

3.数字千分位转换

/*数字格式转换成千分位*/
function numToMicrometer(num) {
    if (trim(num + "") == "") {
        return "";
    }
    if (isNaN(num)) {
        return "";
    }
    num = num + "";
    if (/^.*\..*$/.test(num)) {
        varpointIndex = num.lastIndexOf(".");
        varintPart = num.substring(0, pointIndex);
        varpointPart = num.substring(pointIndex + 1, num.length);
        intPart = intPart + "";
        var re = /(-?\d+)(\d{3})/
        while (re.test(intPart)) {
            intPart = intPart.replace(re, "$1,$2")
        }
        num = intPart + "." + pointPart;
    } else {
        num = num + "";
        var re = /(-?\d+)(\d{3})/
        while (re.test(num)) {
            num = num.replace(re, "$1,$2")
        }
    }
    return num;
}

/*去除千分位*/
function delMicrometer(num) {
    if (trim(num + "") == "") {
        return "";
    }
    num = num.replace(/,/gi, ‘‘);
    return num;
}

4.获取给定字符串占用的字节长度

function getByteLen(val) { // 传入一个字符串
    var len = 0;
    for (var i = 0; i < val.length; i++) {
        if (val[i].match(/[^\x00-\xff]/ig) != null) // 全角
            len += 2; // 如果是全角，占用两个字节
        else
            len += 1; // 半角占用一个字节
    }
    return len;
}

5.构建url参数

/*
param = {
  name1 : value1,
  name2 : value2,
  ...
}
*/
function buildParam(param) {
    var paramContent = ‘‘;
    try {
        if (!empty(param)) {
            for (var key in param) {
                paramContent += key + ‘=‘ + encodeURIComponent(param[key])
                        + ‘&‘;
            }
        }
    } catch (e) {
    }
    return paramContent;
}

6.判断变量是否空值 undefined, null, ‘‘, false, 0, [], {} 均返回true，否则返回false

function empty(v) {
    switch (typeof v) {
        case ‘undefined‘ :
            return true;
        case ‘string‘ :
            if (trim(v).length == 0)
                return true;
            break;
        case ‘boolean‘ :
            if (!v)
                return true;
            break;
        case ‘number‘ :
            if (0 === v)
                return true;
            break;
        case ‘object‘ :
            if (null === v)
                return true;
            if (undefined !== v.length && v.length == 0)
                return true;
            for (var k in v) {
                return false;
            }
            return true;
            break;
    }
    return false;
}

7.去除html标签

/*去除html标记*/
function removeHtmlTag(str) {
    return str.replace(/<[^>]+>/g, "");
}

8.获取url参数(返回数组类型)

function getRequestParam(param) {
    var url = location.search; // 获取url中"?"符后的字串
    var paramStr = new Array();

    if (url.indexOf("?") != -1) {
        var str = url.substr(1);
        strs = str.split("&");
        for (var i = 0; i < strs.length; i++) {
            if (param == strs[i].split("=")[0]) {
                paramStr.push(strs[i].split("=")[1]);
            }
        }
    }
    return paramStr;
}

9.指定字符高亮

function setHighLightText(txt, currentTargetText) {
    if (empty(txt)) {
        return ‘‘;
    }
    var newTxt = txt;
    if (currentTargetText.length != 0) {
        $(currentTargetText).each(function(i) {
            var reg = new RegExp(currentTargetText[i], "g");
            newTxt = newTxt.replace(reg, "<em>" + currentTargetText[i]
                            + "</em>");
        });
    }
    return newTxt;
}

10.替换url中的指定参数

function changeURLArg(url, paramName, paramName_val) {
    var pattern = paramName + ‘=([^&]*)‘;
    var replaceText = paramName + ‘=‘ + paramName_val;
    if (url.match(pattern)) {
        var tmp = ‘/(‘ + paramName + ‘=)([^&]*)/gi‘;
        tmp = url.replace(eval(tmp), replaceText);
        return tmp;
    } else {
        if (url.match(‘[\?]‘)) {
            return url + ‘&‘ + replaceText;
        } else {
            return url + ‘?‘ + replaceText;
        }
    }
    return url + ‘\n‘ + paramName + ‘\n‘ + paramName_val;
}