[Solved-6 Solutions] Convert string to Boolean in javascript - javascript tutorial


How to convert a string to boolean in JavaScript ?

Solution 1:

We use brackets for the value and equal it with isTrueSet

var isTrueSet = (Value == 'true');


We also used strictly equality operator(===) only when the implicit type conversions doesn't need else use normal equality operator (==).

var isTrueSet = (Value === 'true');


Boolean operator used for specific needs so we should probably be cautious about using these two methods.

var myBool = Boolean("false");  // == true

var myBool = !!"false";  // == true
  • It will evaluate to true except the empty string.
  • Otherwise they're the cleanest methods we can think of concerning to boolean conversion.
  • If they are not can we do.

Solution 2:

The solution is technically correct for a normal string. If we passed an invalid json string into the functions then it will throw an exception. In this case we use the below code:


or with jQuery


Solution 3:

  • Another way is to normalize data by using .toLowerCase().
  • Then we want to throw in trim() to strip whitespace.
  • And it is easy to convert string into boolean.
stringToBoolean: function(str){
        case "true": case "yes": case "1": return true;
        case "false": case "no": case "0": case null: return false;
        default: return Boolean(str);

Solution 4:

Use regular expression (/^true$/i) to convert string into boolean

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

In the above solution we extends the String object then we worried about clashing with other code.That why we use Object.defineProperty to release this clashes

Object.defineProperty(String.prototype, "example_bool", {
    get : function() {
        return (/^(true|1)$/i).test(this);

(It Won't work in older version of Firefox)

Solution 5:

Better way to redefine the solution 1 with the case:

var isTrueSet = (myValue.toLowerCase() === 'true');

we can also detect using checkbox.

var isTrueSet = document.myForm.IS_TRUE.checked;

Assuming that if the checkbox is checked, return true else return false.

Solution 6:

The universal way of solve this problem is:

if (String(str) == "true") 

If the string in the uppercase then use:

String(str).toLowerCase() === "true"

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