how to write a function passed as an argument in a constructor?

Question

Hello Javascript Expert.
Here is my problem.
In my code, a constructor makes buttons. Each button have its own function.
How to write paramaters inside object constructor (meaning how to assign onclick attribute) correctly ?

for exemple, function 'moveleft' must be assigned to 'buttonLeft'

// my button constructor:
function buttonConstructor(param1,param2...,action){
this.param1=param1;
...
this.action=action;
this.commandCreate = function(){
var btn = document.createElement("button");
...
btn.setAttribute("onclick", action); //action is assigned to the onclick attribute
};

// button creation
buttonLeft = new buttonConstructor("param1",...,movleft); //how i should write moveleft function assigned to action?)

// function being assigned to 'action' argument
function moveleft() {
myCar.speedX -= 1;
}

regards

Answer 1

Thank you Geoffrey !

But it doesn't work on my side. I think i made something wrong.

Can you explain me why using window here

btn.setAttribute("onclick", window[action]());

Merci !

Answer 2

window[ "functName" ]() is a synthax to trig a function by its name without using the ugly and famous "eval()". Are you in a web environment using that code ? Or are you using javascript in another domain ? Cause "window" superglobal is only available in web.

Answer 3

If you set the 'onclick' attribute of an html element, you must assign to it a string value with the code to execute, not a function.
Anyway, the good way to set an event handler at runtime is to assign a function to the element through its .addEventListener() method.

https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener

Answer 4

I took your example and here is my proposal.
https://code.sololearn.com/WzurseS15TQM/#js