Interview Q&A / JavaScript
JavaScript interview questions
Closures, the event loop, this, promises and the core language questions every frontend round asks.
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- What is the difference between == and === in JavaScript?
=== (strict equality) is true only if both values have the same type and the same value. == (loose equality) first converts the values to a common type and then compares, which gives surprising results like 0 == "" being true. Use === by default.
BeginnerIn-depth3 min read - How is Object.is different from the === operator?
Object.is works like === with two differences: Object.is(NaN, NaN) is true, and Object.is(0, -0) is false. React uses it to compare state values.
IntermediateQuick answer1 min read