ESLintEnforce spacing before and after semicolons (semi-spacing)
JavaScript allows you to place unnecessary spaces before or after a semicolon.
Disallowing or enforcing space around a semicolon can improve the readability of your program.
var a = "b" ;
var c = "d";var e = "f";
Fixable: This rule is automatically fixable using the --fix flag on the command line.
Rule Details
This rule aims to enforce spacing around a semicolon. This rule prevents the use of spaces before a semicolon in expressions.
This rule doesn’t check spacing in the following cases:
-
The spacing after the semicolon if it is the first token in the line.
-
The spacing before the semicolon if it is after an opening parenthesis (
(or{), or the spacing after the semicolon if it is before a closing parenthesis ()or}). That spacing is checked byspace-in-parensorblock-spacing. -
The spacing around the semicolon in a for loop with an empty condition (
for(;;)).
Options
The rule takes one option, an object, which has two keys before and after having boolean values true or false.
If before is true, space is enforced before semicolons and if it’s false, space is disallowed before semicolons.
If after is true, space is enforced after semicolons and if it’s false, space is disallowed after semicolons.
The after option will be only applied if a semicolon is not at the end of line.
The default is {"before": false, "after": true}.
"semi-spacing": [2, {"before": false, "after": true}]
{"before": false, "after": true}
This is the default option. It enforces spacing after semicolons and disallows spacing before semicolons.
The following patterns are considered problems:
/*eslint semi-spacing: 2*/
var foo ; /*error Unexpected whitespace before semicolon.*/
var foo;var bar; /*error Missing whitespace after semicolon.*/
throw new Error("error") ; /*error Unexpected whitespace before semicolon.*/
while (a) { break ; } /*error Unexpected whitespace before semicolon.*/
for (i = 0 ; i < 10 ; i++) {} /*error Unexpected whitespace before semicolon.*/
for (i = 0;i < 10;i++) {} /*error Missing whitespace after semicolon.*/
The following patterns are not considered problems:
/*eslint semi-spacing: 2*/
var foo;
var foo; var bar;
throw new Error("error");
while (a) { break; }
for (i = 0; i < 10; i++) {}
for (;;) {}
if (true) {;}
;foo();
{"before": true, "after": false}
This option enforces spacing before semicolons and disallows spacing after semicolons.
The following patterns are considered problems:
/*eslint semi-spacing: [2, { "before": true, "after": false }]*/
var foo; /*error Missing whitespace before semicolon.*/
var foo ; var bar; /*error Missing whitespace before semicolon.*/ /*error Unexpected whitespace after semicolon.*/
throw new Error("error"); /*error Missing whitespace before semicolon.*/
while (a) { break; } /*error Missing whitespace before semicolon.*/ /*error Unexpected whitespace after semicolon.*/
for (i = 0;i < 10;i++) {} /*error Missing whitespace before semicolon.*/
for (i = 0; i < 10; i++) {} /*error Missing whitespace before semicolon.*/ /*error Unexpected whitespace after semicolon.*/
The following patterns are not considered problems:
/*eslint semi-spacing: [2, { "before": true, "after": false }]*/
var foo ;
var foo ;var bar ;
throw new Error("error") ;
while (a) {break ;}
for (i = 0 ;i < 10 ;i++) {}
When Not To Use It
You can turn this rule off if you are not concerned with the consistency of spacing before or after semicolons.
Related Rules
Version
This rule was introduced in ESLint 0.16.0.