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JavaScript JavaScript and the DOM (Retiring) Making Changes to the DOM Styling Elements

Posted by nathanielcusano
nathanielcusano
9,808 Points

The choice of verbose coding in javascript. Why not do it this way... it worked for me.

const toggLelist= document.getElementById('toggleList');
const listDiv = document.querySelector ('.list');
const input= document.querySelector ('input.description');
const p = document.querySelector ('p')[1];
const button = document.querySelector ('button')[1];

1 Answer

Steven Parker
Steven Parker
229,708 Points
Steven Parker
Steven Parker
229,708 Points

You have some errors, this should not have "worked".

Take this line for example:

const p = document.querySelector('p')[1];

Here you are indexing the result of a call to querySelector, but querySelector returns a single element, not an element collection. The result of this assignment would cause p to be undefined.

Even if you substituted querySelectorAll (which returns a collection) and the intended target element was the second paragraph, this code might work as-is but would be fragile and easily broken by the addition of new paragraph elements. The video example of using a combined class and tag in the selector would be much more robust.

nathanielcusano
nathanielcusano
9,808 Points

Ok thanks but lets say I had like 5 more paragraphs. Wouldn't a need to differentiate them with a different class name every time? Also I thought that querySelector only selects the first <p> element so what does it matter if there are 5 more paragraphs? I don't understand this. Is it possible to just type in the arrays I want like [0, 2, 3] or something. I don't understand the superiority of class, can you help me lol?

Steven Parker
Steven Parker
229,708 Points
Steven Parker
Steven Parker
229,708 Points

The advantage of the class is that you can associate it with a particular paragraph, and that will be reliable even if other paragraphs get added in front of it. If you rely on indexing, you would have to update your code when anything is added to the document, even if (and especially if) it was not intended to be affected by the code.

If you wanted paragraphs treated differently, class names make sense; but if you want them all treated the same, then you might use a querySelectorAll and loop through them.

And yes, querySelector only selects the first element, and that's why you cannot use an index with it.