JS-028
Visual JavaScript guide to Number(): Learn how to convert values to numbers using Number()
Beginner3 min~3 min read#number#type-conversion#casting

Number()

Converting to a number

Goal

Learn how to convert values to numbers using Number().

Explanation

  • Number() converts a value to the number type.
  • It is most often used to convert text entered by the user.
  • If a string contains a valid number, the conversion succeeds.
  • After conversion, you can perform math operations on the value.
  • If conversion is not possible, JavaScript returns NaN.

Analogy

Imagine a card with "42" written on it. Number() reads the text and turns it into the actual number 42.

Code

console.log(Number("42"));
console.log(Number("100"));

Result: 42 100

Common mistake

Beginners often think Number() works with any text. For example, Number("Hello") returns NaN.

Remember

  • ✦ Number() creates a number.
  • ✦ "42" and 42 are different data types.
  • ✦ Invalid values may produce NaN.

Quick Quiz

What does Number("42") return?

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