How Can I Safely Convert a String to a Boolean in JavaScript?

Converting a String to Boolean in JavaScript: A Comprehensive Guide

In JavaScript, it's essential to accurately handle the conversion of strings representing boolean values into intrinsic boolean types. This is particularly crucial when working with hidden forms that obtain boolean values from user input, which often results in string representations.

To address this need, let's delve into various techniques for string-to-boolean conversion.

Recommended Approach: Using the Identity Operator

The identity operator, denoted by ===, offers a reliable method for boolean conversion. It maintains type safety by avoiding implicit conversions, ensuring that 'true' equates to true and 'false' equates to false.

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

Additional Case-Insensitive Options

To make the conversion case-insensitive, consider:

var isTrueSet = /^true$/i.test(myValue);

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

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

Cautions

While certain methods may seem convenient, they exhibit drawbacks:

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

var myBool = !!"false";  // == true

These methods evaluate any non-empty string as true, making them unsuitable for precise boolean conversion.

Suggestion

To determine the boolean value of a string that represents a boolean, it's advisable to depend on the literal string representations of 'true' or 'false.' However, for greater flexibility, consider incorporating the identity operator into your code.

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