What are the differences between ==, ===, and Object.is() in JavaScript?

Differences Between ==, ===, and Object.is()

== (Loose Equality)

Performs type coercion before comparing:

0 == false        // true (false converts to 0)
'' == false       // true
null == undefined // true
1 == '1'          // true ('1' converts to 1)

=== (Strict Equality)

No type coercion — both type and value must be identical:

0 === false        // false (different types)
1 === '1'          // false (different types)
null === undefined // false (different types)
NaN === NaN        // false (special NaN behavior)

Object.is()

Behaves like === but fixes two edge cases:

Object.is(NaN, NaN)   // true  (=== gives false)
Object.is(+0, -0)     // false (=== gives true)
Object.is(1, 1)       // true
Object.is(null, null) // true

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Summary

Comparison	==	===	Object.is()
Type coercion	✅ Yes	❌ No	❌ No
NaN vs NaN	false	false	true
+0 vs -0	true	true	false

Always prefer ===. Use Object.is() only for precise NaN and ±0 handling.