Type Conversion

Type Conversion — Implicit vs Explicit

JavaScript is a dynamically typed language, which means it often converts types automatically (implicit coercion). Sometimes that's helpful. Other times it's a source of head-scratching bugs. You can also convert types explicitly using built-in functions.

Explicit Boolean Conversion

console.log(Boolean(1));
console.log(Boolean(0));
console.log(Boolean("hello"));
console.log(Boolean(""));

Explicit String Conversion

console.log(String(123));
console.log(String(true));
console.log(String(null));
console.log(String(undefined));

Explicit Number Conversion

console.log(Number("123"));
console.log(Number("12.5"));
console.log(Number("hello"));
console.log(Number(true));
console.log(Number(false));

Implicit Arithmetic Coercion

console.log("5" - 2);
console.log("5" * "3");
console.log("10" / 2);
console.log("5" + 2); // Watch out! + is string concatenation

Pro tip: use + on a string to convert it to a number: +"5" gives 5.