The answer
Because the + operator favors string concatenation. When one operand is a string, the other is coerced to a string, so 1 becomes '1' and the result is '12'.
JavaScript Is Weakly Typed: What That Means
Why does 1 + '2' give '12' in JavaScript?
More FAQs in JavaScript Is Weakly Typed: What That Means
Variables can hold any type and change types at runtime. The engine coerces values automatically when types do not match, which can lead to unexpected results like 1 + '2' = '12'.
== coerces operands to a common type before comparing, so '0' == 0 is true. === checks both type and value without coercion, so '0' === 0 is false. Always prefer ===.
Dynamically and weakly typed. Types are checked at runtime, not compile time, and the engine coerces values automatically when types mismatch.
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