Javascript-Custom Errors
Custom errors in JavaScript are 8 types of error objects. which are raised in a try or catch expression depending on the error type. They are:
- Error
- EvalError
- RangeError
- ReferenceError
- SyntaxError
- TypeError
- URIError
- I analyzed them
Error:
This is a generic error. It’s the one all the other error objects inherit from.
It contains 2 properties:
message: Human-readable message that should explain what error happened.
name: Type of error occurred (the value of the particular error object name(TypeError / SyntaxError)).
EvalError:
It was used to specify that the global function eval() was used incorrectly and in a way incompatible with its definition.
RangeError:
A RangeError will fire and when a numeric value is not in its range of allowed values.
set an array length to a negative value:
[].length = -1 //RangeError: Invalid array length
set it to a number higher than 4294967295:
[].length = 4294967295 //4294967295 [].length = 4294967296 //RangeError: Invalid array length
most common range errors:
RangeError: Not a valid code point.
RangeError: invalid array length.
RangeError: invalid date.
RangeError: precision is out of range.
RangeError: radix must be an integer.
RangeError: repeat count must be less than infinity.
RangeError: repeat count must be non-negative.
ReferenceError:
It is indicated that an invalid reference value has been detected. A JavaScript programming language is trying to read a variable that does not exist.
dog //ReferenceError: dog is not defined dog = 2 //ReferenceError: dog is not defined
most common reference errors:
ReferenceError: “x” is not defined.
ReferenceError: assignment to undeclared variable “x”.
ReferenceError: can’t access lexical declaration ‘X’ before initialization.
ReferenceError: deprecated caller or argument usage.
ReferenceError: invalid assignment left-hand side.
ReferenceError: reference to undefined property “x”.
SyntaxError:
It is raised when a syntax error is found in a program.
function statement without name:
function() {
return 'Hi!'
}
//SyntaxError: function statement requires a name
comma after an object property:
const dog = {
name: 'Roger'
age: 5
}
//SyntaxError: missing } after property list
common syntax errors:
SyntaxError: “0”-prefixed octal literals and octal escape seq. are deprecated
SyntaxError: “use strict” not allowed in function(non-simple parameters).
SyntaxError: “x” is a reserved identifier.
SyntaxError: JSON.parse: bad parsing.
SyntaxError: Malformed formal parameter.
SyntaxError: Unexpected token.
SyntaxError: //@ to indicate source URL pragmas is deprecated. Use //# instead.
SyntaxError: illegal character.
SyntaxError: invalid regular expression flag “x”.
SyntaxError: missing ) after argument list.
SyntaxError: missing ) after condition.
SyntaxError: missing : after property id.
SyntaxError: missing ; before statement.
SyntaxError: missing = in const declaration.
SyntaxError: missing \] after element list.
SyntaxError: missing formal parameter.
SyntaxError: missing name after . operator.
SyntaxError: missing variable name.
SyntaxError: missing } after function body.
SyntaxError: missing } after property list.
SyntaxError: redeclaration of formal parameter “x”.
SyntaxError: return not in function.
TypeError:
It happens when a value has a type that is different than the one expected.
trying to invoke a number:
1() //TypeError: 1 is not a function
common type errors:
TypeError: “x” has no properties
TypeError: “x” is (not) “y”
TypeError: “x” is not a constructor
TypeError: “x” is not a function
TypeError: “x” is not a non-null object
TypeError: “x” is read-only
TypeError: ‘x’ is not iterable
TypeError: More arguments needed
TypeError: invalid arguments
TypeError: cyclic object value
URIError:
It is raised when returning one of the global function() that work with URIs:
- decodeURI()
- decodeURIComponent()
- encodeURI()
- encodeURIComponent()
and passing an invalid URI.