prevent window.onload being overridden javascript

Question

How to overcome event handlers being overridden? I have a script say a.js

window.onload = function () {
   //Handler in a.js
}

Another script say b.js

window.onload = function () {
   //Handler in b.js
}

where,

a.js is a kind of 3rd party library built by me

b.js is a publisher who uses my script [I can't do any changes out here]

Will onload handler in b.js override a.js's handler?

If yes, How to prevent this from happening?

Will building a queue of all event handlers in a.js and deque them on event help?

But will a.js know all event handlers for an event upfront untill b.js is loaded?

Thoughts and references would help

Answer 1

you should use addEventListener() to have various handlers for the same event

window.addEventListener("load", yourfunction, false);