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In JavaScript you create a TypeError instance using the constructor TypeError.

Description

Creates a TypeError object when a variable or parameter is not of a valid type.

Syntax

Parameters

Class Properties

Instance Properties

Class Methods

None.

Instance Methods

None.

Examples

Let's look at some examples of throwing a type error within our code.

// Throw an error.
try {
  throw new TypeError();
} catch (e) {
    alert('A type error: ' + e.name);
}  

// Throw an error with a message.
try {
  throw new TypeError('Throwing a type error.');
} catch (e) {
    alert('A type error with message: ' + e.name + ': ' + e.message);
}  

We can also create our own TypeError instances as the example below shows.

// Create our own TypeError object.
function ourTypeError(message) {  
  this.name = 'OurTypeError';  
  this.message = message || 'Default Message Used When No Message Passed';
}   

// Inherit from the TypeError prototype.
ourTypeError.prototype = new TypeError();  
ourTypeError.prototype.constructor = ourTypeError;   

// Throw an error.
try {  
  throw new ourTypeError();  
} catch (e) {  
  alert('Our Error: ' + e.name + ' Message: ' + e.message);
}   

// Throw an error and a message.
try {  
  throw new ourTypeError('A Message we have passed');  
} catch (e) {  
  alert('Our Error: ' + e.name + ' Our Message: ' + e.message);
} finally {  
  alert('A finally statement will always be executed!');
}   

Related Tutorials

JavaScript Advanced Tutorials - Lesson 2 - Errors

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