Legacy generator function

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.

Obsolete since Gecko 58 (Firefox 58 / Thunderbird 58 / SeaMonkey 2.55)
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

The legacy generator function was a SpiderMonkey-specific feature, which is removed in Firefox 58+. For future-facing usages, consider using function*.

The legacy generator function statement declares legacy generator functions with the specified parameters.

You can also define functions using the Function constructor with functionBody and at least one yield expression, and a legacy generator function expression.

Syntax

function name([param,[, param,[..., param]]]) {
   [statements]
}
name
The function name.
param
The name of an argument to be passed to the function. A function can have up to 255 arguments.
statements
The statements which comprise the body of the function. This should contain at least one yield expression.

Description

An overview of the usage is available on the Iterators and Generators page.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
Legacy generator function
DeprecatedNon-standard
Chrome No support NoEdge No support NoFirefox No support 2 — 58IE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android No support NoFirefox Android No support 4 — 58Opera Android No support NoSafari iOS No support NoSamsung Internet Android No support Nonodejs No support No

Legend

No support  
No support
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.
Deprecated. Not for use in new websites.
Deprecated. Not for use in new websites.

See also

Related Topics
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  13. Errors
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    10. ReferenceError: "x" is not defined
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    16. SyntaxError: "0"-prefixed octal literals and octal escape seq. are deprecated
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    59. TypeError: can't delete non-configurable array element
    60. TypeError: can't redefine non-configurable property "x"
    61. TypeError: cannot use 'in' operator to search for 'x' in 'y'
    62. TypeError: cyclic object value
    63. TypeError: invalid 'instanceof' operand 'x'
    64. TypeError: invalid Array.prototype.sort argument
    65. TypeError: invalid arguments
    66. TypeError: invalid assignment to const "x"
    67. TypeError: property "x" is non-configurable and can't be deleted
    68. TypeError: setting getter-only property "x"
    69. TypeError: variable "x" redeclares argument
    70. URIError: malformed URI sequence
    71. Warning: -file- is being assigned a //# sourceMappingURL, but already has one
    72. Warning: 08/09 is not a legal ECMA-262 octal constant
    73. Warning: Date.prototype.toLocaleFormat is deprecated
    74. Warning: JavaScript 1.6's for-each-in loops are deprecated
    75. Warning: String.x is deprecated; use String.prototype.x instead
    76. Warning: expression closures are deprecated
    77. Warning: unreachable code after return statement
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