Javascript: Correct syntax in for

Question

I have this code:

$(this).find('.placeholder-style td:nth-child(1)').addClass('hidden-td')
$(this).find('.placeholder-style td:nth-child(2)').addClass('hidden-td')
$(this).find('.placeholder-style td:nth-child(3)').addClass('hidden-td')
$(this).find('.placeholder-style td:nth-child(4)').addClass('hidden-td')
$(this).find('.placeholder-style td:nth-child(5)').addClass('hidden-td')

And I want to do it dynamic like this:

for (i = 0; i < 5; i++){
   $(this).find('.placeholder-style td:nth-child'.(i)).addClass('hidden-td')
}

Which is the correct syntax to this code?

Just change the starting value to 1 instead of 0 and use <= instead of <. And use string concatenation (as indicated by Teemu below). And don't forget to use var i. — JLRishe
– JLRishe, Commented Nov 20, 2017 at 11:16
+ operator has used to be a string concatenation operator in JS ... — Teemu
– Teemu, Commented Nov 20, 2017 at 11:17
Most jQuery methods implicitly iterate over the collection, so I'd rather try to narrow down the matches, then call addClass once on the right set of elements, e.g. $(this).find('.placeholder-style td').filter( function(idx){ return idx < 5 }).addClass('hidden-td') — pawel
– pawel, Commented Nov 20, 2017 at 11:21

Quentin · Accepted Answer · 2017-11-20 11:18:36Z

3

In JavaScript, the concatenation operator is + not .
The ( and ) are part of the selector syntax, not JavaScript syntax, they need to be strings.

Such

$(this).find(
    '.placeholder-style td:nth-child(' + i + ')' 
).addClass('hidden-td')

This would probably be easier to do without the for loop.

$(this).find(
    '.placeholder-style td:not(:nth-child(6) ~ td)' 
).addClass('hidden-td')

answered Nov 20, 2017 at 11:18

Quentin

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5 Comments

Quentin Over a year ago

@LluísPuigFerrer — The loop should be exactly as it is in the question. jsbin.com/masuvuluvi/1/edit?html,css,js,output

Lluís Puig Ferrer Over a year ago

Thanks @Quentin for you answer and explanation. Your jsbin works, I'm checking in my real code and is not working. I will put here a link to my other question and maybe you can help me.

Lluís Puig Ferrer Over a year ago

stackoverflow.com/questions/47329008/…

Lluís Puig Ferrer Over a year ago

With your second answer works, but not with for. Can check it?

Lluís Puig Ferrer Over a year ago

I know why is not working. I'm using in for a variable which I get like this: ` var numcells = $('.hidden-td').length ` but in blade I have a foreach so I get all the .hidden-td of blade not in the row. Know how can I do it?

Ramesh Rajendran · Accepted Answer · 2017-11-20 11:28:27Z

1

Should define i variable like var i
The i value should be start with 1
use + instead of . for concatenate string

just like,

for ( var i = 1; i <= 5; i++){
   $(this).find('.placeholder-style td:nth-child'+i).addClass('hidden-td')
}

answered Nov 20, 2017 at 11:28

Ramesh Rajendran

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Comments

Ivan Karaman · Accepted Answer · 2017-11-20 11:22:39Z

0

I think u can do this in easier way

.placeholder-style td:nth-child(-n+5){display: none;}

answered Nov 20, 2017 at 11:22

Ivan Karaman

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