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What is increment (++) operator in JavaScript?
The increment operator (++) increases a numeric value by one. It comes in two forms: pre-increment (++variable) and post-increment (variable++), which behave differently in expressions.
Syntax
++variable // Pre-increment: increment first, then return value variable++ // Post-increment: return value first, then increment
Pre-increment vs Post-increment
<html>
<body>
<script>
let a = 5;
let b = 5;
document.write("Pre-increment (++a): " + ++a + "<br>");
document.write("Value of a after: " + a + "<br><br>");
document.write("Post-increment (b++): " + b++ + "<br>");
document.write("Value of b after: " + b);
</script>
</body>
</html>
Pre-increment (++a): 6 Value of a after: 6 Post-increment (b++): 5 Value of b after: 6
Key Difference in Expressions
<html>
<body>
<script>
let x = 10;
let y = 10;
let result1 = x + ++x; // Pre-increment
document.write("x + ++x = " + result1 + "<br>");
let result2 = y + y++; // Post-increment
document.write("y + y++ = " + result2);
</script>
</body>
</html>
x + ++x = 21 y + y++ = 20
Comparison
| Operator | When increment happens | Value returned |
|---|---|---|
++variable |
Before use | New value |
variable++ |
After use | Original value |
Conclusion
Use pre-increment (++) when you need the incremented value immediately, and post-increment (++) when you need the original value first. Both forms increase the variable by one.
Updated on: 2026-03-15T21:37:29+05:30
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