javascript - What is the best way to test for an empty string with jquery-out-of-the-box? - Stack Overflow

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What is the best way to test for an empty string with jquery-out-of-the-box, i.e. without plugins? I tried this.

But it did't work at least out-of-the-box. It would be nice to use something that's builtin.

I wouldn't like to repeat

if (a == null || a=='')

everywhere if some if (isempty(a)) would be available.

What is the best way to test for an empty string with jquery-out-of-the-box, i.e. without plugins? I tried this.

But it did't work at least out-of-the-box. It would be nice to use something that's builtin.

I wouldn't like to repeat

if (a == null || a=='')

everywhere if some if (isempty(a)) would be available.

• javascript
• jquery

Share Improve this question Follow edited Jun 14, 2017 at 13:31 itzmebibin 9,43999 gold badges5151 silver badges6262 bronze badges asked Nov 28, 2009 at 10:59 MartinMartin 2,95344 gold badges2222 silver badges1515 bronze badges 2

• 1 possible duplicate of What is the best way to check for an empty string in JavaScript? – Adriano Carneiro Commented Oct 28, 2011 at 15:34
• Possible duplicate of How do you check for an empty string in JavaScript? – T.Todua Commented Dec 4, 2018 at 9:33

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10 Answers 10

Sorted by: Reset to default 605

if (!a) {
  // is emtpy
}

To ignore white space for strings:

if (!a.trim()) {
    // is empty or whitespace
}

If you need legacy support (IE8-) for trim(), use $.trim or a polyfill.

The link you gave seems to be attempting something different to the test you are trying to avoid repeating.

if (a == null || a=='')

tests if the string is an empty string or null. The article you linked to tests if the string consists entirely of whitespace (or is empty).

The test you described can be replaced by:

if (!a)

Because in javascript, an empty string, and null, both evaluate to false in a boolean context.

Based on David's answer I personally like to check the given object first if it is a string at all. Otherwise calling .trim() on a not existing object would throw an exception:

function isEmpty(value) {
  return typeof value == 'string' && !value.trim() || typeof value == 'undefined' || value === null;
}

Usage:

isEmpty(undefined); // true
isEmpty(null); // true
isEmpty(''); // true
isEmpty('foo'); // false
isEmpty(1); // false
isEmpty(0); // false

Check if data is a empty string (and ignore any white space) with jQuery:

function isBlank( data ) {
    return ( $.trim(data).length == 0 );
}

if(!my_string){ 
// stuff 
}

and

if(my_string !== "")

if you want to accept null but reject empty

EDIT: woops, forgot your condition is if it IS empty

Try executing this in your browser console or in a node.js repl.

var string = ' ';
string ? true : false;
//-> true

string = '';
string ? true : false;
//-> false

Therefore, a simple branching construct will suffice for the test.

if(string) {
    // string is not empty
}

Since you can also input numbers as well as fixed type strings, the answer should actually be:

function isBlank(value) {
  return $.trim(value);
}

Please see this code by jQuery:

 if ($("#ItemId").val().trim() != "") {
            console.log($("#ItemId").val());
        }

Try this

if(!a || a.length === 0)

if((a.trim()=="")||(a=="")||(a==null))
{
    //empty condition
}
else
{
    //working condition
}

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