Enforce spacing around the * in generator functions (generator-star-spacing)
The --fix
option on the command line can automatically fix some of the problems reported by this rule.
Generators are a new type of function in ECMAScript 6 that can return multiple values over time. These special functions are indicated by placing an *
after the function
keyword.
Here is an example of a generator function:
/*eslint-env es6*/
function* generator() {
yield "44";
yield "55";
}
This is also valid:
/*eslint-env es6*/
function *generator() {
yield "44";
yield "55";
}
This is valid as well:
/*eslint-env es6*/
function * generator() {
yield "44";
yield "55";
}
To keep a sense of consistency when using generators this rule enforces a single position for the *
.
Rule Details
This rule aims to enforce spacing around the *
of generator functions.
Options
The rule takes one option, an object, which has two keys before
and after
having boolean values true
or false
.
before
enforces spacing between the*
and thefunction
keyword. If it istrue
, a space is required, otherwise spaces are disallowed.In object literal shorthand methods, spacing before the
*
is not checked, as they lack afunction
keyword.after
enforces spacing between the*
and the function name (or the opening parenthesis for anonymous generator functions). If it istrue
, a space is required, otherwise spaces are disallowed.
The default is {"before": true, "after": false}
.
An example configuration:
"generator-star-spacing": ["error", {"before": true, "after": false}]
And the option has shorthand as a string keyword:
{"before": true, "after": false}
→"before"
{"before": false, "after": true}
→"after"
{"before": true, "after": true}
→"both"
{"before": false, "after": false}
→"neither"
An example of shorthand configuration:
"generator-star-spacing": ["error", "after"]
Examples
before
Examples of correct code for this rule with the "before"
option:
/*eslint generator-star-spacing: ["error", {"before": true, "after": false}]*/
/*eslint-env es6*/
function *generator() {}
var anonymous = function *() {};
var shorthand = { *generator() {} };
after
Examples of correct code for this rule with the "after"
option:
/*eslint generator-star-spacing: ["error", {"before": false, "after": true}]*/
/*eslint-env es6*/
function* generator() {}
var anonymous = function* () {};
var shorthand = { * generator() {} };
both
Examples of correct code for this rule with the "both"
option:
/*eslint generator-star-spacing: ["error", {"before": true, "after": true}]*/
/*eslint-env es6*/
function * generator() {}
var anonymous = function * () {};
var shorthand = { * generator() {} };
neither
Examples of correct code for this rule with the "neither"
option:
/*eslint generator-star-spacing: ["error", {"before": false, "after": false}]*/
/*eslint-env es6*/
function*generator() {}
var anonymous = function*() {};
var shorthand = { *generator() {} };
When Not To Use It
If your project will not be using generators or you are not concerned with spacing consistency, you do not need this rule.
Further Reading
Version
This rule was introduced in ESLint 0.17.0.