jQuery JavaScript is there a function like parseInt for Boolean

Question

I know, I know, sounds silly, but I am having this one variable passed around and around and I think somewhere in the midst of it all its losing itself as a Boolean Value, that being the case I need to take said string when it comes to one portion of my script and make sure its read as a Boolean. So with that, I am wondering if theres something like the parseInt function but for booleans cause I know when my int's manage to get run through the mill and turn into a string cause of, I sometimes need to invoke a means of making it recognize as integer again.

score 3 · Accepted Answer · answered Jun 15 '12 at 01:40

3

String.prototype.parseBoolean = function ()
{
  return ("true" == this.toLowerCase()) ? true : false
}

answered Jun 15 '12 at 01:40

odiszapc

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2

adding to native objects prototype is generally frowned upon these days http://stackoverflow.com/questions/6877005/extending-object-prototype-javascript - also can be simplified by getting rid of the ternary statement and just returning the comparison. – mkoryak Jun 15 '12 at 02:29

mkoryak · Answer 2 · 2012-06-15T02:23:57.980

2

no there is no function, there is this shortcut:

var bool = !!something;

or, you can make a new boolean like this:

var bool = Boolean(something)

it works by coercing the value to a boolean. It will use the truthy/falsy value for the variable.

while i am on this topic, there is also:

var floor = ~~3.1415; //floor = 3

edited Jun 15 '12 at 02:23

answered Jun 15 '12 at 02:14

mkoryak

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Warning if anyone stumbles on this: !!"false" === true. And Boolean("false") === true. – tru7 Feb 22 '21 at 19:31

score 0 · Answer 3 · answered Jun 15 '12 at 01:50

function stringToBoolean(string){
    if (typeof string === "undefined") {
        console.log("stringToBoolean Undefined Error");
        return false;
    }
    if (typeof string === "boolean") return string;
    switch(string.toLowerCase()) {
        case "true": case "yes": case "1": return true;
        case "false": case "no": case "0": case null: return false;
        default: return false;
    }
}

jQuery JavaScript is there a function like parseInt for Boolean

3 Answers3