Javascript get length of an array of fields with a array keys in it

Question

I have a simple form with an array in it:

<form id='my_form'>
    <input type="text" name="my_array[1]">
    <input type="text" name="my_array[5]">
    <input type="text" name="my_array[6]">
    <input type="text" name="non_array_field">
</form>

As you can see the array keys are specified

How can I get the lenght of this array? I can use javascript or jquery

These only works if the array doesn't have keys:

document.querySelectorAll("[name='my_array[]']").length
document.formName.elements["my_array[]"].length

Tushar · Accepted Answer · 2015-11-17 11:00:40Z

2

Use attribute-starts with selector. To select only the elements inside form, use form selector.

[attr^=value]

Represents an element with an attribute name of attr and whose value is prefixed by "value".

document.querySelectorAll("#my_form [name^='my_array[']").length

var len = document.querySelectorAll('#my_form [name^="my_array["]').length;
console.log(len);

<form id='my_form'>
  <input type="text" name="my_array[1]">
  <input type="text" name="my_array[5]">
  <input type="text" name="my_array[6]">
  <input type="text" name="non_array_field">
</form>

Using jQuery

Docs

$("#my_form [name^='my_array[']").length

var len = $('#my_form [name^="my_array["]').length;
console.log(len);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<form id='my_form'>
  <input type="text" name="my_array[1]">
  <input type="text" name="my_array[5]">
  <input type="text" name="my_array[6]">
  <input type="text" name="non_array_field">
</form>

edited Nov 17, 2015 at 11:00

answered Nov 17, 2015 at 10:55

Tushar

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1 Comment

Tushar Over a year ago

To use regex in selector see Pass Regex To JQuery Selector

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