Decoding JavaScript Errors
Errors in JavaScript are inevitable, but understanding them can make debugging easier. JavaScript has several built-in error types that can help you identify what went wrong in your code.
ReferenceError
A ReferenceError
is thrown when trying to dereference a variable that has not been declared.
console.log(nonExistentVariable) // Outputs: ReferenceError: nonExistentVariable is not defined
TypeError
A TypeError
is thrown when an operation could not be performed, typically when a value is not of the expected type.
null.f() // Outputs: TypeError: Cannot read property 'f' of null
SyntaxError
A SyntaxError
is thrown when trying to execute code with a syntactical error.
eval('hoo bar') // Outputs: SyntaxError: Unexpected identifier
RangeError
A RangeError
is thrown when a numeric variable or parameter is outside of its valid range.
new Array(-1) // Outputs: RangeError: Invalid array length
Understanding these error types can help you debug your JavaScript code more effectively.