Question

I don’t know why I have an function like:

<script type="text/javascript">
    function setSomeEnvValue() {
        myLoadStatus = true;
        myColor = 'black';
    }
    window.onload = setSomeEnvValue();
</script>

I don’t know why IE show error at:

window.onload = setSomeEnvValue();

When I change this code to:

window.onload = setSomeEnvValue;

It makes me crazy. If setSomeEnvValue() has some arguments like setSomeEnvValue(myVar1, myVar2), how can I call it when using it in IE?

Thanks you very much!

Answer 1

In this case, IE has the correct implementation.

When you set a callback (or event handler), such as window.onload, you’re basically telling the browser that the function that you’re giving it should be executed when that event is triggered.

By writing window.onload = setSomeEnvValue();, you’re saying that the return value of setSomeEnvValue should be called whenever the window.onload event is triggered. Of course, this may be possible if your function returns a closure, but I’m going to assume that’s not the case here.