js动态检测加载 JQ

版权声明：吃火星的宝宝 代码记录，转载请说明出处！ https://blog.csdn.net/embaobao/article/details/80920130

var jqcdnurl = 'https://cdn.bootcss.com/jquery/3.2.1/jquery.js';
//控制台输出
function log() {
    for (var index in arguments) {
        console.log(arguments[index]);
    }
}
//js加载 fun
function loadjs() {
    arguments[0]();
    for (var index in arguments) {
        if (index != 0) {
            document.write("<scr" + "ipt src=\"" + arguments[index] + "\"></sc" + "ript>");
            log("java script :" + arguments[index] + " -> please waiting,loading...↓")
        }
    }
}

//异常处理函数 fun
function catchErro() {
    try {
        if (arguments.length > 0) {
            arguments[0]();
        }

    } catch (err) {
        if (arguments.length > 1) {
            arguments[1](err);
        }

    } finally {
        if (arguments.length > 2) {
            arguments[2]();
        }

    }
}

//是否具有jq 环境 fun
function isHasJq() {
    return typeof (jQuery) == "undefined" ? false : true;
}

//动态加载js fun
function loadScript(url, callback) {
    var script = document.createElement("script");
    script.type = "text/javascript";
    if (typeof (callback) != "undefined") {
        if (script.readyState) {
            script.onreadystatechange = function () {
                if (script.readyState == "loaded" || script.readyState == "complete") {
                    script.onreadystatechange = null;
                    callback();
                }
            };
        } else {
            script.onload = function () {
                callback();
            };
        }
    };
    script.src = url;
    document.body.appendChild(script);
}

//是否存在此src js fun
function isHasjsBysrc(url) {
    var ishave = false;
    var headscripts = document.getElementsByTagName('script');
    for (var index in headscripts) {


        if (headscripts[index].src == url) {
            ishave = true
        }
        log("引入脚本:" + headscripts[index].src);

    }
    log("JQ 脚本状态:" + ishave);
    return ishave;
}
//加载jqcdn #废除 fun
function appendJQCDN() {
    if (!isHasjsBysrc("https://cdn.bootcss.com/jquery/1.10.2/jquery.min.js")) {
        var head = document.head || document.getElementsByTagName('head')[0];
        var script = document.createElement('script');
        var style = document.createElement('style');
        script.setAttribute("src", "https://cdn.bootcss.com/jquery/1.10.2/jquery.min.js");
        style.innerHTML = '';
        head.appendChild(script);
        head.appendChild(style);
        log("JQ CDN 引入成功！ ");
    }
}

//动态加载JQ并执行 fun
function dynamicAddJQExcute(excuteFUN) {
    loadScript(jqcdnurl, excuteFUN);
    log("JQ ALL Ready!");
}


//加载js
loadjs(function () {
    log("cs_base-js load ok!", "loading done");
}, "js/csopp.js", "js/cstip.js");

//JQ执行函数
function ExcuteCs(fun) {
    if (isHasJq()) {
        $(document).ready(function () {
            fun();
        });
    } else {
        dynamicAddJQExcute(function () {
            $(document).ready(function () {
                fun();
            });
        });

    }
}

document.onload = catchErro(
    function () {
        if (isHasJq()) {
            log("JQ ALL Ready!");
        } else throw ex;
    },
    function (ex) {
        log("没有引入 JQ 环境,请引入JQ 环境", "动态引入.... (未在网络状态则无法动态引用)" ,"建议手动引入,否则造成未知错误，对此不负任何责任");
    }
);

ExcuteCs(function(){
	$("body").html("TEST");
});