Can't get element value by id

[kullar84]

I can't get element value by id if id value contains "[number]". Lets say i have input field:

<input type="text" name="USERNAME[0]" id="USERNAME[0]" value="username" />

When I call alert($('#USERNAME[0]').val()); then it says undefined, but if I use this example:

<input type="text" name="USERNAME2" id="USERNAME2" value="username2" />

and call alert($('#USERNAME2').val()); then I get correct value.

Little example:  http://office.5dvision.ee/~kullar/Testid/jQuery_Test/jquery.php

[DDaviesBrackett]

you are falling afoul of the escaping rules: jQuery interprets [] as indices, so you'll need to specify your hardcoded square brackets as \[\] to jQuery (which means you'll need to write
[
] into the string).

Try alert($('#USERNAME
[0
]').val()); .

[dmethvin]

Solution is provided in the comment above, and in the jQuery documentation.