Convert string to Boolean in javascript [duplicate]

Answer 1

you can also use JSON.parse() function

JSON.parse("true") returns true (Boolean)

JSON.parse("false") return false (Boolean)

Answer 2

See this question for reference:

How can I convert a string to boolean in JavaScript?

There are a few ways:

// Watch case sensitivity!
var boolVal = (string == "true");

or

var boolVal = Boolean("false");

or

String.prototype.bool = function() {
    return (/^true$/i).test(this);
};
alert("true".bool());

Answer 3

I believe the following code will do the work.

function isBoolean(foo) {
    if((foo + "") == 'true' || (foo + "") == 'false') {
        foo = (foo + "") == 'true';
    } else { 
        console.log("The variable does not have a boolean value.");
        return;
    }
    return foo;
}

Explaining the code:

foo + ""

converts the variable 'foo' to a string so if it is already boolean the function will not return an invalid result.

(foo + "") == 'true'

This comparison will return true only if 'foo' is equal to 'true' or true (string or boolean). Note that it is case-sensitive so 'True' or any other variation will result in false.

(foo + "") == 'true' || (foo + "") == 'false'

Similarly, the sentence above will result in true only if the variable 'foo' is equal to 'true', true, 'false' or false. So any other value like 'test' will return false and then it will not run the code inside the 'if' statement. This makes sure that only boolean values (string or not) will be considered.

In the 3rd line, the value of 'foo' is finally "converted" to boolean.

Answer 4

I would like to answer this to improve upon the accepted answer.

To improve performance, and in real world cases where form inputs might be passing values like 'true', or 'false', this method will produce the best results.

function stringToBool(val) {
    return (val + '').toLowerCase() === 'true';
}

JSPerf

Answer 5

trick string to boolean conversion in javascript. e.g.

var bool= "true";
console.log(bool==true) //false

var bool_con = JSON.parse(bool);

console.log(bool_con==true) //true

Answer 6

These lines give the following output:

Boolean(1).toString(); // true
Boolean(0).toString(); // false