Javascript Dont Change The Background

Question

I want to change my list background but it wont work

my code :

change(num, element){
var text

if (num == 1){ ... }
else if (num == 2) { ... }
else { ... }

document.getElementById('text').innerHTML = text;

document.getElementByClass("left").style.backgroundColor = "black"; //<------ 
element.style.backgroundColor = "white";                            //<------
}

and my html :

<ul>
   <li><a class="left" href="#" onclick="change(1,this)>First</a></li>
   <li><a class="left" href="#" onclick="change(2,this)>Second</a></li>
   <li><a class="left" href="#" onclick="change(3,this)>Third</a></li>      
</ul>

When i click on one of my list element , the text changes but background color won't ...

How i can fix this ?

Thanks,

Open your browser's developer tools. Look at the console. Read the error messages. Call a function that actually exists! Then look at the duplicate question for your second problem. — Quentin, Jul 12 '16 at 12:10
correct: document.getElementsByClassName(), (it returns array) You are using document.getElementByClassName() (s missing) — Dinesh Patra, Jul 12 '16 at 12:11
@DineshPatra — getElementsByClassName doesn't return an array, just something that is like an array in some ways. — Quentin, Jul 12 '16 at 12:12
@Quentin, in the console (in this page) as there is a element with class name 'default', I tried this typeof(document.getElementsByClassName('default')); it is returning object, But I need to access innerHTML by document.getElementsByClassName('default')[0].innerHTML; So i think its array' Also as per https://developer.mozilla.org/en-US/docs/Web/API/Document/getElementsByClassName it says array like object — Dinesh Patra, Jul 12 '16 at 12:16
@DineshPatra — If you try `document.getElementsByClassName('default') instanceof Array` then you'll see that it is not an array. If you try `document.getElementsByClassName('default').forEach(...)` then it will error, but all arrays have a `forEach` method. It does not return an array. — Quentin, Jul 12 '16 at 12:18
@DineshPatra — It says "array like object" and not "array" because it is not an array. — Quentin, Jul 12 '16 at 12:18
@Quentin thank you for ur clarification. As per it's usage, I thought its array. But frankly I had only once used this. Otherwise I use document.querySelector(); — Dinesh Patra, Jul 12 '16 at 12:20

score 0 · Accepted Answer · answered Jul 12 '16 at 12:11

0

There's no such function as getElementByClass, there's only getElementsByClassName, wich returns an array. You need to choose the one you want to change out of this array or use ids

answered Jul 12 '16 at 12:11

Bálint

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Javascript Dont Change The Background

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