Do I need to check for null and length, or is there a shorter way to check for a non-empty string?

Question

I set the value of the #thimble hidden field when the page loads using values ​​on the server side.

Then in JavaScript, I want to work on this value only if it was filled with some non-empty string.

Is this the shortest way to verify that a value is not empty?

 if ($("#thimble").val() != null && $("#thimble").val().length > 0) { carryOn(); } 

Seems pretty long.

Answer 1

An empty string is false, I would not even bother to check its length .

The following is an example:

 if ($("#thimble").val()) { carryOn(); } 

False is a value that expresses false when evaluated in a boolean context (for example, the condition of an if ).

Falsey Values:

• null
• undefined
• NaN
• 0
• "" (empty string)
• false

Remember that a string in a boolean context creates false only when its length is 0 , if it has a space, it creates true anyway:

 Boolean(""); // false Boolean(" "); // true, whitespace 

Answer 2

If for $.trim - .length you mean everything except zero length or space, use $.trim with .length

 if ($.trim($("#thimble").val()).length) { ... } 

Answer 3

 if ($("#thimble").val().length) { carryOn(); }