Leo Leo - 2 months ago 8
jQuery Question

Setting bool value to input and getting string type via javascript/jquery

When I get a value or set a value (from the server side, for example) for an input that is a boolean type it comes as "True" or "False" instead of true or false.

For example:

var isDated = $('.someClass').val();

//will not pass because isDated is a string
if (isDated == true){

Why does this happend?
Which is the best way to avoid this?


I've found a blog that has a solution to avoid this problem:

Below a prototype method called .toBoolean() to validate true/false when it comes as a string based on some responses from this post:

String.prototype.toBoolean = function ()
var dictionary = { "True": true, "False": false };
return dictionary[this];

Boolean.prototype.toBoolean = function () {
return this;

Number.prototype.toBoolean = function () {
return this;


If you want to know why C# outputs True and False instead of the lowercase versions, see this question.

If you want to know why it's not converted to a boolean value, it's because all <input> elements' values are considered text by JavaScript. It's up to you to convert it into another type. With checkboxes/radio buttons that's already done by using the .checked attribute (for jQuery, either $('.someClass').is(':checked') or $('.someClass').prop('checked') will work). Otherwise, the best way would be comparing the value to a string, and using that, for example: if ($('.someClass').val().toLowerCase() === 'true').