JS-019
Educational JavaScript lesson graphic for Plus Operator +: Understand how the + operator works with numbers and strings
Beginner3 min~3 min read#plus#addition#string

Plus Operator +

Adds numbers or joins text

Goal

Understand how the + operator works with numbers and strings.

Explanation

  • The + operator can do two different jobs.
  • If both values are numbers, it adds them.
  • If at least one value is a string, it joins the text together.
  • So the same operator can behave differently.
  • JavaScript decides which mode to use on its own.

Analogy

Imagine a universal glue. It can either put two numbers together, or stick two pieces of text side by side.

Code

console.log(5 + 3);

console.log("Hello" + "!");

Result: 8 Hello!

Common mistake

Beginners often expect + to always add numbers. If one of the values is a string, JavaScript will concatenate text instead.

Remember

  • ✦ + adds numbers.
  • ✦ + joins strings.
  • ✦ The behavior depends on the data types.

Quick Quiz

What does "5" + 3 return?

Resources