What is the difference between SyntaxError, ReferenceError, and TypeError in JavaScript?
SyntaxError is caught at parse time (malformed code, const without initializer, re-declaration). ReferenceError is at runtime (variable does not exist or is in TDZ). TypeError is at runtime (value is wrong type for the operation, reassigning const).
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More FAQs in SyntaxError vs ReferenceError vs TypeError in JavaScript
Because the engine catches it during parsing, before any code runs. 'const x;' is malformed syntax (const requires an initializer), so it is a SyntaxError, not a runtime ReferenceError.
Because the variable exists (no ReferenceError), but the operation (assignment) is not allowed for a const. The value's type (const binding) does not support reassignment, so it is a TypeError.
ReferenceError: Cannot access 'x' before initialization. The message is different from 'not defined', but it is still a ReferenceError because the variable reference cannot be resolved to a value.
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