How to convert a string to boolean in javascript / Various ways to convert a string to boolean in javascript

There are situations in which we have a boolean value in string format (‘true’ or ‘false’) and we want its boolean equivalent (such as true or false).
Practical application is when we have a check condition value which is stored as a string in database and based on this value we want to perform some operation on our html page (or jsp).

Off course, we can compare the string returned from database with ‘true’ and ‘false’ and get a boolean as a result but this may not be a perfect solution.
Below, I have tried to collect some approaches to achieve this. Read On !!!

Method 1 : Using test method

var stringValue = "true";
var boolValue = (/true/i).test(stringValue) //returns true

Detail: test method of javascript matches a regular expression against a string. In this case we check whether the string contains true or not. Now, if the string value is ‘true’, then boolValue will be true, else a false. /i at the end of regular expression is for case insensitive match.

Method 2 : Using comparison operator

var stringValue = "true";
var boolValue = (stringValue =="true");   //returns true

Detail : We are using javascript equality operator to check the string value against a ‘true’. If the string value is ‘true’, then the boolean value will also have a true, else a false.
Method 3 : Using JSON.parse

var stringValue = "true";
var boolValue = JSON.parse(stringValue);   //returns true

Detail : Here we use the parse method of JSON. JSON is a built-in object of javascript and its parse method parses a string as JSON and converts it into an object corresponding to the given text. So, if the string value is ‘true’, it is converted to a boolean object with value as true and false otherwise.

Tired of reading… Watch video!!!

Method 4 : Using ternary operator

var stringValue = "true";
var boolValue = stringValue.toLowerCase() == 'true' ? true : false;   //returns true

Detail : Here, we simply check the string for its equality with ‘true’ and return a boolean true if there is a match and false otherwise using a ternary operator.

Method 5 : Using switch-case

var stringValue = "true";
var boolValue = getBoolean(stringValue); //returns true
function getBoolean(value){
   switch(value){
        case true:
        case "true":
        case 1:
        case "1":
        case "on":
        case "yes":
            return true;
        default: 
            return false;
    }
}

Detail : A switch-case construct is used to cover all possible string value combinations which should lead to a true boolean value.
Though we have used many string combinations for true condition but you may reduce them based on the string values stored by your application. That is, if your application will only use the value ‘true’, then you don’t need other combinations such as 1, ‘on’ etc.
If the given string (‘true’) matches, then the corresponding boolean is returned and boolean false is returned in every other case.
This article explained different methods to parse a string to a boolean in javascript. Conversion of string to number in javascript can also be done in many different ways.
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