Trying to number objects in jQuery

Question

I'm trying to number objects, which can be added to a cart with drag'n'drop. So, this snippet should check the current number written in span.amountVal, and easily add ´+1´ to this number, but the result is always ´1´. When I uncomment the ´alert(i++);´, the snippet work like I want to. I'm confused, what is this about?

$.favList.find("div[data-asset-id="+ _itemID +"]").each(function() {
    var i = $(this).find("span.amountVal").text();

    // alert(i++);

    $(this).find("span.amountVal").text(i++);
});

Thank you.

JJJ · Accepted Answer · 2012-02-12 16:47:51Z

2

i++ first returns the value of i, then increments it. When you have the alert( i++ ) in place, the variable is already once incremented.

Put the ++ in front of the variable:

$(this).find("span.amountVal").text( ++i );

Or simply add one to it since you're discarding the variable right after:

$(this).find("span.amountVal").text( i + 1 );

answered Feb 12, 2012 at 16:47

JJJ

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1 Comment

Thomaszter Over a year ago

the ++i thing did it, thank you. We will never learned out :)

Community · Accepted Answer · 2017-05-23 12:20:02Z

2

you have a pre-increment/post-increment issue, the following change should solve it:

$.favList.find("div[data-asset-id="+ _itemID +"]").each(function() {
    var i = $(this).find("span.amountVal").text();

    $(this).find("span.amountVal").text(++i);
});

Pre-Increment adds one to i and then returns i while Post-Increment adds 1 to i after it has been returned.

Below is a similar post on StackOverflow touching on the topic:

post increment vs pre increment - Javascript Optimization

edited May 23, 2017 at 12:20

CommunityBot

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answered Feb 12, 2012 at 16:47

Alex

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Comments

Eliseu Monar dos Santos · Accepted Answer · 2012-02-12 17:43:39Z

0

What are you guys doing? It SHOULDN'T read a SPAN's value, it's bad practice. Instead, it should read the items length (inside an object, for example) and then display it.

answered Feb 12, 2012 at 17:43

Eliseu Monar dos Santos

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