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Core JavaScriptBeginner

Type Coercion

Type coercion is JavaScript converting one value type into another during operations or comparisons.

JavaScript sometimes converts values automatically. For example, string concatenation can convert numbers to strings, and loose equality can coerce values before comparing them. Understanding coercion helps you predict odd outputs and write code that is explicit instead of surprising.

Explanation

JavaScript sometimes converts values automatically. For example, string concatenation can convert numbers to strings, and loose equality can coerce values before comparing them. Understanding coercion helps you predict odd outputs and write code that is explicit instead of surprising.

Key Points

  • The `+` operator concatenates if one side is a string.
  • Loose equality may convert values before comparing them.
  • Explicit conversion with `Number`, `String`, or `Boolean` is usually clearer.

Common Mistakes

  • Expecting `"5" + 1` to perform numeric addition.
  • Using loose equality without understanding the conversion rules.
  • Confusing truthy or falsy behavior with actual boolean values.

Practice Workspace

type-coercion.js

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Editor

3 lines

Output

0 entries

Mode

practice

Workspace Notes

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type-coercion.js
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Editor Actions

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Console0 entries

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Expected Output

51
6
true

Continue in Playground

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Related Concepts

Data Types

JavaScript has primitive and reference data types, and knowing the difference affects comparison, copying, and mutation.

Equality

JavaScript has loose and strict equality, and they behave differently because loose equality allows coercion.

Truthy and Falsy

JavaScript treats some values as truthy and some as falsy when evaluating conditions.