Type Conversion

Converting between data types

Goal

Learn how to convert values between different data types.

Explanation

JavaScript lets you change a value's type.
The functions Number(), String(), and Boolean() are used for this.
They create a new value of a different type.
Type conversion is common when working with forms, APIs, and user input.
Understanding type conversion helps you avoid unexpected program behavior.

Analogy

Imagine water. You can pour it from a glass into a bottle or a cup. The content stays the same, but the container changes. JavaScript can change a value's type the same way.

Code

console.log(Number("42"));
console.log(String(42));
console.log(Boolean(0));

Result: 42 "42" false

Common mistake

Not every string can be converted to a number. For example, Number("Hello") returns NaN.

Remember

✦ Number() creates a number.
✦ String() creates a string.
✦ Boolean() creates a boolean value.
✦ A value's type can be changed.

Quick Quiz

Which function converts the string "42" to a number?

Resources

📘MDN — Type conversion