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array-methodseasy

What is the difference between == and ===?

Answer

=== compares type and value with no conversion. == coerces the operands to a common type first, which produces surprises like '' == 0 and '1' == 1 being true. Use === by default. The one common exception is x == null, which is a concise way to test for null or undefined together.

Points an interviewer listens for

  • === strict: no coercion
  • == coerces, producing non-obvious truths
  • Default to ===
  • x == null is a deliberate, useful exception

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