javascript doesnt execute code after for

Question

I have created 2 functions in javascript, these functions are fired on click events, the problem is that after the for loops, alerts are not executed.

function myfunc() {
    for (var i = 0; i < 4; i++) {
        document.getElementsByTagName("h1")[i].style.color="red";
    }

    alert("alert 1"); //this should be executed after the for since it is part of the function code.
}

function myfunc2() {
    for (var j = 0; j < 4; j++) {
        document.getElementsByTagName("h1")[j].style.color="navy";		
    }

    alert("alert 2"); //this should be executed after the for since it is part of the function code
}

<h1 onClick="myfunc()">primo h1</h1>
<h1 onClick="myfunc2();">secondo h1</h1>

Are the bodies of the loop executed? the attribute is usually written onclick (without a capital letter), I don't know if the case is important. — Aaron
– Aaron, Commented May 21, 2016 at 0:30
Changing the length as @MaxStarkenburg suggested, works fine. Get the length using something like: var h1Len = document.getElementsByTagName("h1").length; and use insted of the hardcoded number — trinaldi
– trinaldi, Commented May 21, 2016 at 0:34

undefined · Accepted Answer · 2016-05-21 01:15:30Z

1

You need to check how many h1 tags there are in the DOM before applying new style attributes. You are effectively trying to make changes to undefined.

var elements = document.getElementsByTagName("h1");

function myfunc() {
    for (var i = 0; i < elements.length; i++) {
        elements[i].style.color="red";
    }

    alert("alert 1"); //this should be executed after the for since it is part of the function code.
}

function myfunc2() {
    for (var j = 0; j < elements.length; j++) {
        elements[j].style.color="navy";
    }

    alert("alert 2"); //this should be executed after the for since it is part of the function code
}

<h1 onClick="myfunc()">primo h1</h1>
<h1 onClick="myfunc2();">secondo h1</h1>

edited May 21, 2016 at 1:15

answered May 21, 2016 at 0:42

undefined

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2 Comments

Felipe Skinner Over a year ago

why would you store the DOM node on a elements var and call from the DOM once again inside the for-loop instead of using your elements

undefined Over a year ago

It was a quick copy from the original question. Corrected.

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