Using javascript variable in jquery selector

Question

I have a <form> with this input...

Term ID: <input type="text" name="data_array[0][term_id]" size="5" value="' . $highest_term_id . '">

where $highest_term_id is set by PHP.

I'm trying to use jquery to increment the "data_array[0]" part by...

$("input[data_array[" + index + "][term_id]").val((index + 1));

but I get this error:

Error: Syntax error, unrecognized expression: input[data_array[undefined][term_id]"

A bit higher in the script I have var index = 0;;

Any ideas why this is failing?

Joe Enos · Accepted Answer · 2016-08-10 18:44:15Z

1

The square bracket has special meaning in jQuery selectors - you'll have to escape them - should be something like:

$("input[name=data_array\\[" + index + "\\]\\[term_id\\]]").val((index + 1));

I'd try to avoid this naming convention if possible, or try to find an alternative to selecting it by name - as you can see, it's hard to keep the brackets and backslashes straight when referencing it.

answered Aug 10, 2016 at 18:44

Joe Enos

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6 Comments

gtilflm Over a year ago

The error is gone now, but the increment part isn't working. Thanks for the info about the [ ]s though.

Joe Enos Over a year ago

When you say "increment", you're not incrementing anything here - you're just saying index + 1. Are you trying to do ++index?

gtilflm Over a year ago

Sorry... yeah. A bit later in the code I do index++;.

gtilflm Over a year ago

Tried $("input[data_array\\[0\\]\\[term_id\\]").val(); in Firebug (Firefox) and it's returning null.

Joe Enos Over a year ago

The selector is still wrong - the data_array[0][term_id] is the name of the tag, so your selector should be looking at name. Look at my example again.

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