Web/JavaScript/Reference/Global objects/Error/toSource

Non-standard This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The toSource() method returns code that could eval to the same error.

Syntax

e.toSource()

Return value

A string containing the source code of the error.

Examples

Using toSource

Calling the toSource method of an Error instance (including NativeErrors) will return a string containing the source code of the error. This string can be evaluated to create an (approximately) equal object. Naturally, the string containing the source follows the structure of the Error constructor. For example:

(newname(message ,fileName,lineNumber))

where these attributes correspond to the respective properties of the error instance.

Note: Be aware that the properties used by the toSource method in the creation of this string are mutable and may not accurately reflect the function used to create an error instance or the filename or line number where the actual error occurred.

Specifications

Not part of any standard.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`toSource` Non-standard'	Chrome No support No	Edge No support No	Firefox No support 1 — 74 Notes' No support 1 — 74 Notes' Notes' Starting in Firefox 74, `toSource()` is no longer available for use by web content. It is still allowed for internal and privileged code.	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No	nodejs No support No

Legend

Full support: Full support
No support: No support
Non-standard. Expect poor cross-browser support.': Non-standard. Expect poor cross-browser support.
See implementation notes.': See implementation notes.