Js方法集

收集一些經常使用方法，思之補之踩過的坑；

 

斷定瀏覽器是否爲移動端，而後to do something:

$(function isMobileBrowser()
{
    var sUserAgent = navigator.userAgent.toLowerCase();    
    var bIsIpad = sUserAgent.match(/ipad/i) == "ipad";    
    var bIsIphoneOs = sUserAgent.match(/iphone os/i) == "iphone os";    
    var bIsMidp = sUserAgent.match(/midp/i) == "midp";    
    var bIsUc7 = sUserAgent.match(/rv:1.2.3.4/i) == "rv:1.2.3.4";    
    var bIsUc = sUserAgent.match(/ucweb/i) == "ucweb";    
    var bIsAndroid = sUserAgent.match(/android/i) == "android";    
    var bIsCE = sUserAgent.match(/windows ce/i) == "windows ce";    
    var bIsWM = sUserAgent.match(/windows mobile/i) == "windows mobile";    
    if (bIsIpad || bIsIphoneOs || bIsMidp || bIsUc7 || bIsUc || bIsAndroid || bIsCE || bIsWM ){    
        return true;
    }else 
        return false;
})()

曾經的錯誤…，js能夠獲取上一個訪問的頁面，可用於多個場景，而且刷新頁面此值不變：

document.referrer

js中計算一些帶小數的數字會得出小數點很是長的現象例如2.01-1.02=0.9899999999999998，由於js中是將數字轉成二進制進行計算而後再轉成數字：

var ComputAmount = function(arg1, arg2, computType) {
    var r1, r2, m;
    try {
        r1 = arg1.toString().split(".")[1].length
    } catch(e) {
        r1 = 0
    }
    try {
        r2 = arg2.toString().split(".")[1].length
    } catch(e) {
        r2 = 0
    }
    m = Math.pow(10, Math.max(r1, r2))
    if(computType == 1) {
        return((arg1 * m + arg2 * m) / m).toFixed(2);
    } else {
        return((arg1 * m - arg2 * m) / m).toFixed(2);
    }
}

三個參數，第一個數字，第二個數字，第三個是加減的參數，改動能夠用於乘除；

 

判斷url是否存在某search參數，稍改動可獲取某search參數的值：

function giveQuery(p) {
    var httppath = "www.baidu.com?a=b&c=d",
        httppath = httppath.substring(13); //?a=b&c=d  此處可優化
    //var httppath=location.search; //?a=b&c=d
    search = httppath.length > 0 ? httppath.substring(1) : "", //a=b&c=d
        items = search.length > 0 ? search.split("&") : [], //["a=b", "c=d"]
        item = null,
        t = false,
        len = items.length; //2
 
    for(i = 0; i < len; i++) {
        item = items[i].split("=");
        if(item[0] == p) {
            console.log(item[1]);
            t = true;
        }
    }
    if(!t) {
        console.log("search is null")
    }
}

讀取Cookie值：

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

瀏覽器居中顯示提示消息，移動端應用的多些：

var alertMsg = function(text) {
    //拼接div 或者display div 
    //class=alertBg 設置透明蒙版等
    $("body").append('<div class="alertBg" id="alertMsg">' + text + '</div>');
 
    var $height = $("#alertMsg").outerHeight() / 2,
        $width = $("#alertMsg").outerWidth() / 2;
 
    $("#alertMsg").css({
        marginLeft: -$width,
        marginTop: -$height
    });
 
    $("#alertMsg").show().fadeOut(3000, function() {
        $(this).remove();
    });
}

舊版瀏覽器(IE678)提示：

var isIE7older = document.all && !document.querySelector,
isIE8older = document.all && document.querySelector && !document.addEventListener;
if(isIE7older || isIE8older) {
    doSomeThing()
}

原版 2017-03-07發佈於xuechenlei.com