what's the role of slice method here ? why need it?

Asked Jul 27 '20 at 19:32

Active Jul 27 '20 at 20:33

Viewed 74 times

In ES5 if have a NodeList and want to loop through it must first convert it to Array with slice and call. I can't understand correctly how this statement works. I need explanation.

let nodeList = document.querySelectorAll('div');
let nToArr   = Array.prototype.slice.call(nodeList);
// Then Loop Through it ....

edited Jul 27 '20 at 19:55

asked Jul 27 '20 at 19:32

Youssef Hany

1

This is might help: https://stackoverflow.com/questions/13295361/why-do-array-prototype-slice-callnodelist-for-dom-elements – Ameya Rane Jul 27 '20 at 19:35
2

I'd start with the documentation: [`slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice), [`call`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/call) – Heretic Monkey Jul 27 '20 at 19:36
Why not `Array.from(nodeList)` ? – George Jul 27 '20 at 19:37
you can also just do [...nodeList] to transform it into an array. – Talmacel Marian Silviu Jul 27 '20 at 19:38
Or [`NodeList.forEach`](https://developer.mozilla.org/en-US/docs/Web/API/NodeList/forEach) for that matter... – Heretic Monkey Jul 27 '20 at 19:38
2

I think Array.from was introduced in Es6, so maybe this is to include browsers that don't support that? – Ameya Rane Jul 27 '20 at 19:39
i already know Array.form , i need to know how that line work each segment of it – Youssef Hany Jul 27 '20 at 19:42
why use slice ? – Youssef Hany Jul 27 '20 at 19:42
@canon okay ! how does this specific thing work ? – Youssef Hany Jul 27 '20 at 19:46
3

the slice function is used to normally extract a subarray from an array. But by setting the this value ( call(nodeList)) as the nodelist, we're tricking the function into making a shallow copy of the nodelist as an array. – Ameya Rane Jul 27 '20 at 19:48
@canon You misunderstood :D , you understood my intention, could you explain it to me? – Youssef Hany Jul 27 '20 at 19:49
@Ameya Rane Thanks , that's what i need , actually i wrote the question without specification – Youssef Hany Jul 27 '20 at 19:52

what's the role of slice method here ? why need it?

0 Answers0