Question

I use window.onload in the my script which contains other call functions

window.onload = function() {
            maxHeight_main_column();
...
}

and added my script in the head tag

In the body I added new script from other site which uses window.onload again, and my window.onload works good but second window.onload doesn’t work, how I can resolve this problem?

I can’t edit second file with window.onlad

Answer 1

There can only be one function assigned to window.onload. But, you can have multiple event listeners that listen to that same event.

// cross browser way to add an event listener
function addListener(event, obj, fn) {
    if (obj.addEventListener) {
        obj.addEventListener(event, fn, false);   // modern browsers
    } else {
        obj.attachEvent("on"+event, fn);          // older versions of IE
    }
}

addListener('load', window, myFunc1);    // you can have multiple ones of these
addListener('load', window, myFunc2);    // you can have multiple ones of these
window.onload = myFunc3;                 // one and only one of these

See the MDN doc on addEventListener for more details.

In your specific case, you can use this code for your onload handler and let the other one use window.onload:

// cross browser way to add an event listener
function addListener(event, obj, fn) {
    if (obj.addEventListener) {
        obj.addEventListener(event, fn, false);   // modern browsers
    } else {
        obj.attachEvent("on"+event, fn);          // older versions of IE
    }
}
addListener('load', window, function() {
    maxHeight_main_column();
    ...
});