window.onload is only used once, so there will be conflicts when multiple js use it at the same time.
Solution

1.用jQuery使用ready()方法替换onload
2.在window.onload中一次加载所有js文件，例：window.onload=function(){function(a);function(b);} 

I tried it. The window can be bound multiple times, but it will only take effect the last time. You can compare my two examples below to understand your situation.

    //方式1:
    window.onload=function () {
        console.log("1");
    }
    window.onload=function () {
        console.log("2");
    }
//    输出2
//    -------------------------------分割线
//    方式2:
    function fn1() {
        console.log("1");
    }
    function fn2() {
        console.log("2");
    }
    addEventLoad(fn1);
    addEventLoad(fn2);
    //输出1  2
    function addEventLoad(fn){
        var oldFn = window.onload;
        if(typeof window.onload != 'function'){
            window.onload = fn;
        }else{
            window.onload = function(){
                oldFn();
                fn();
            }
        }
    }

• For events set through the window.onload = function() { ... } method, the later window.onload value will overwrite the previous one, so only the last one will take effect. (This is the same as calling a = 1; a = 2; a =3; )

• If you need to bind the onload event of window multiple times, it is recommended to use addEventListener:

window.addEventListener('load', function() { ... }, false);

• Note that attachEvent is used in the ID instead of addEventListener:

window.attachEvent('onload', function() { ... });

• Also note that 'load' is used in addEventListener, while 'onload' is used in attachEvent.

The window.onload() method can only be bound once. If you bind multiple times, only the last one will take effect

window.onload will only call the last one, and the previous ones will be overwritten.