Showing an element when visible with jQuery

Question

What does the + 1 means in this example? In this statement: if ($('.hideme').index($(this)) + 1 === $('.hideme').length)

http://jsfiddle.net/e5qaD/1151/

It's from the answer of one of the questions here, on stackoverflow: Show Div when scroll position

It adds one to `$('.hideme').index($(this))` and compares it to `$('.hideme').length`. — Sebastian Simon, Dec 19 '16 at 19:44
Do you really mean, why is the +1 needed? Because as to what +1 "means", well, it adds one. — Tim Grant, Dec 19 '16 at 19:45
Why the water is wet? I think he ment Why is he adding 1 not What the code means. — DiegoS, Dec 19 '16 at 19:46
length show count of elements, but numbering began from zero, 10 elements with 0 - 9 indexes, length return 10, index return index of element in array (9 + 1 === 10)... — Ivan Karaman, Dec 19 '16 at 19:48

Abhinav Galodha · Accepted Answer · 2016-12-19T19:50:04.893

2

index starts from Zero, and the length Property for a non-empty element starts from 1.

Jquery index method Searches for a given element from among the matched elements.

From Jquery Documentation

If a selector string is passed as an argument, .index() returns an integer indicating the position of the first element within the jQuery object relative to the elements matched by the selector. If the element is not found, .index() will return -1.

In most Programming languages, the index starts from 0. So, the index returned would be always 1 less than the actual number.

edited Dec 19 '16 at 19:50

answered Dec 19 '16 at 19:46

Abhinav Galodha

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Thanks! I got it now – mikefromnl Dec 19 '16 at 19:48

score 0 · Answer 2 · answered Dec 19 '16 at 19:47

It's to do with how we number elements in programming. When counting in arrays we start from 0

<div></div> 0
<div></div> 1
<div></div> 2
<div></div> 3
<div></div> 4

However, if you want to know how many there are there are 5. So you can add 1 to the answer to get the correct result count

Showing an element when visible with jQuery

2 Answers2