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

Question

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:

//"True"
var isDated = $('.someClass').val();


//will not pass because isDated is a string
if (isDated == true){
    console.log("passed");
}

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

EDIT:

I've found a blog that has a solution to avoid this problem: http://www.peterbe.com/plog/data-and-attr-in-jquery

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 ()
{
    if (this) {
        return true;
    }

    return false;
};

Leo: Please refrain from making minor/ superfluous edits to your question. — Matt
– Matt, Commented Sep 18, 2015 at 7:57

Community · Accepted Answer · 2017-05-23 11:48:19Z

10

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').

edited May 23, 2017 at 11:48

CommunityBot

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answered Sep 14, 2015 at 18:58

Pluto

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2 Comments

codeandcloud Over a year ago

great answer. var isDated = ($('.someClass').val().toLowerCase()=== "true"); would be the ideal converter

Salman Arshad Over a year ago

or this var isDated = {"True": true, "False": false}[$('.someClass').val()];

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