TypeError

The TypeError object represents an error when an operation could not be performed, typically (but not exclusively) when a value is not of the expected type.

Syntax

new TypeError([message[, fileName[, lineNumber]]])

Parameters

message Optional

Optional. Human-readable description of the error

fileName Optional

Optional. The name of the file containing the code that caused the exception

lineNumber Optional

Optional. The line number of the code that caused the exception

Description

A TypeError may be thrown when:

• an operand or argument passed to a function is incompatible with the type expected by that operator or function; or 
• when attempting to modify a value that cannot be changed; or
• when attempting to use a value in an inappropriate way.

Properties

TypeError.prototype

Allows the addition of properties to a TypeError object.

Methods

The global TypeError contains no methods of its own. However, it does inherit some methods through the prototype chain.

TypeError instances

Properties

Examples

Catching a TypeError

try {
  null.f() 
} catch (e) {
  console.log(e instanceof TypeError)  // true
  console.log(e.message)               // "null has no properties"
  console.log(e.name)                  // "TypeError"
  console.log(e.fileName)              // "Scratchpad/1"
  console.log(e.lineNumber)            // 2
  console.log(e.columnNumber)          // 2
  console.log(e.stack)                 // "@Scratchpad/2:2:3\n"
}

Creating a TypeError

try {
  throw new TypeError('Hello', "someFile.js", 10) 
} catch (e) {
  console.log(e instanceof TypeError)  // true
  console.log(e.message)               // "Hello"
  console.log(e.name)                  // "TypeError"
  console.log(e.fileName)              // "someFile.js"
  console.log(e.lineNumber)            // 10
  console.log(e.columnNumber)          // 0
  console.log(e.stack)                 // "@Scratchpad/2:2:9\n"
}

Specifications

Browser compatibility

See also

• Error