ESLint comes with several built-in formatters to control the appearance of the linting results, and supports third-party formatters as well.
You can specify a formatter using the --format or -f flag on the command line. For example, --format codeframe uses the codeframe formatter.
The built-in formatter options are:
Examples of each formatter were created from linting fullOfProblems.js using the .eslintrc configuration shown below.
fullOfProblems.jsfunction addOne(i) {
if (i != NaN) {
return i ++
} else {
return
}
}; .eslintrc:{
"extends": "eslint:recommended",
"rules": {
"consistent-return": 2,
"indent" : [1, 4],
"no-else-return" : 1,
"semi" : [1, "always"],
"space-unary-ops" : 2
}
} <?xml version="1.0" encoding="utf-8"?><checkstyle version="4.3"><file name="/var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js"><error line="1" column="10" severity="error" message="'addOne' is defined but never used. (no-unused-vars)" source="eslint.rules.no-unused-vars" /><error line="2" column="9" severity="error" message="Use the isNaN function to compare with NaN. (use-isnan)" source="eslint.rules.use-isnan" /><error line="3" column="16" severity="error" message="Unexpected space before unary operator '++'. (space-unary-ops)" source="eslint.rules.space-unary-ops" /><error line="3" column="20" severity="warning" message="Missing semicolon. (semi)" source="eslint.rules.semi" /><error line="4" column="12" severity="warning" message="Unnecessary 'else' after 'return'. (no-else-return)" source="eslint.rules.no-else-return" /><error line="5" column="1" severity="warning" message="Expected indentation of 8 spaces but found 6. (indent)" source="eslint.rules.indent" /><error line="5" column="7" severity="error" message="Function 'addOne' expected a return value. (consistent-return)" source="eslint.rules.consistent-return" /><error line="5" column="13" severity="warning" message="Missing semicolon. (semi)" source="eslint.rules.semi" /><error line="7" column="2" severity="error" message="Unnecessary semicolon. (no-extra-semi)" source="eslint.rules.no-extra-semi" /></file></checkstyle>
error: 'addOne' is defined but never used (no-unused-vars) at fullOfProblems.js:1:10:
> 1 | function addOne(i) {
| ^
2 | if (i != NaN) {
3 | return i ++
4 | } else {
error: Use the isNaN function to compare with NaN (use-isnan) at fullOfProblems.js:2:9:
1 | function addOne(i) {
> 2 | if (i != NaN) {
| ^
3 | return i ++
4 | } else {
5 | return
error: Unexpected space before unary operator '++' (space-unary-ops) at fullOfProblems.js:3:16:
1 | function addOne(i) {
2 | if (i != NaN) {
> 3 | return i ++
| ^
4 | } else {
5 | return
6 | }
warning: Missing semicolon (semi) at fullOfProblems.js:3:20:
1 | function addOne(i) {
2 | if (i != NaN) {
> 3 | return i ++
| ^
4 | } else {
5 | return
6 | }
warning: Unnecessary 'else' after 'return' (no-else-return) at fullOfProblems.js:4:12:
2 | if (i != NaN) {
3 | return i ++
> 4 | } else {
| ^
5 | return
6 | }
7 | };
warning: Expected indentation of 8 spaces but found 6 (indent) at fullOfProblems.js:5:1:
3 | return i ++
4 | } else {
> 5 | return
| ^
6 | }
7 | };
error: Function 'addOne' expected a return value (consistent-return) at fullOfProblems.js:5:7:
3 | return i ++
4 | } else {
> 5 | return
| ^
6 | }
7 | };
warning: Missing semicolon (semi) at fullOfProblems.js:5:13:
3 | return i ++
4 | } else {
> 5 | return
| ^
6 | }
7 | };
error: Unnecessary semicolon (no-extra-semi) at fullOfProblems.js:7:2:
5 | return
6 | }
> 7 | };
| ^
5 errors and 4 warnings found.
2 errors and 4 warnings potentially fixable with the `--fix` option. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 1, col 10, Error - 'addOne' is defined but never used. (no-unused-vars) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 2, col 9, Error - Use the isNaN function to compare with NaN. (use-isnan) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 3, col 16, Error - Unexpected space before unary operator '++'. (space-unary-ops) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 3, col 20, Warning - Missing semicolon. (semi) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 4, col 12, Warning - Unnecessary 'else' after 'return'. (no-else-return) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 5, col 1, Warning - Expected indentation of 8 spaces but found 6. (indent) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 5, col 7, Error - Function 'addOne' expected a return value. (consistent-return) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 5, col 13, Warning - Missing semicolon. (semi) /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js: line 7, col 2, Error - Unnecessary semicolon. (no-extra-semi) 9 problems
<?xml version="1.0" encoding="utf-8"?><jslint><file name="/var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js"><issue line="1" char="10" evidence="function addOne(i) {" reason="'addOne' is defined but never used. (no-unused-vars)" /><issue line="2" char="9" evidence=" if (i != NaN) {" reason="Use the isNaN function to compare with NaN. (use-isnan)" /><issue line="3" char="16" evidence=" return i ++" reason="Unexpected space before unary operator '++'. (space-unary-ops)" /><issue line="3" char="20" evidence=" return i ++" reason="Missing semicolon. (semi)" /><issue line="4" char="12" evidence=" } else {" reason="Unnecessary 'else' after 'return'. (no-else-return)" /><issue line="5" char="1" evidence=" return" reason="Expected indentation of 8 spaces but found 6. (indent)" /><issue line="5" char="7" evidence=" return" reason="Function 'addOne' expected a return value. (consistent-return)" /><issue line="5" char="13" evidence=" return" reason="Missing semicolon. (semi)" /><issue line="7" char="2" evidence="};" reason="Unnecessary semicolon. (no-extra-semi)" /></file></jslint> [{"filePath":"/var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js","messages":[{"ruleId":"no-unused-vars","severity":2,"message":"'addOne' is defined but never used.","line":1,"column":10,"nodeType":"Identifier","source":"function addOne(i) {","endLine":1,"endColumn":16},{"ruleId":"use-isnan","severity":2,"message":"Use the isNaN function to compare with NaN.","line":2,"column":9,"nodeType":"BinaryExpression","source":" if (i != NaN) {","endLine":2,"endColumn":17},{"ruleId":"space-unary-ops","severity":2,"message":"Unexpected space before unary operator '++'.","line":3,"column":16,"nodeType":"UpdateExpression","source":" return i ++","endLine":3,"endColumn":20,"fix":{"range":[57,58],"text":""}},{"ruleId":"semi","severity":1,"message":"Missing semicolon.","line":3,"column":20,"nodeType":"ReturnStatement","source":" return i ++","fix":{"range":[60,60],"text":";"}},{"ruleId":"no-else-return","severity":1,"message":"Unnecessary 'else' after 'return'.","line":4,"column":12,"nodeType":"BlockStatement","source":" } else {","endLine":6,"endColumn":6,"fix":{"range":[0,94],"text":"function addOne(i) {\n if (i != NaN) {\n return i ++\n } \n return\n \n}"}},{"ruleId":"indent","severity":1,"message":"Expected indentation of 8 spaces but found 6.","line":5,"column":1,"nodeType":"Keyword","source":" return","endLine":5,"endColumn":7,"fix":{"range":[74,80],"text":" "}},{"ruleId":"consistent-return","severity":2,"message":"Function 'addOne' expected a return value.","line":5,"column":7,"nodeType":"ReturnStatement","source":" return","endLine":5,"endColumn":13},{"ruleId":"semi","severity":1,"message":"Missing semicolon.","line":5,"column":13,"nodeType":"ReturnStatement","source":" return","fix":{"range":[86,86],"text":";"}},{"ruleId":"no-extra-semi","severity":2,"message":"Unnecessary semicolon.","line":7,"column":2,"nodeType":"EmptyStatement","source":"};","endLine":7,"endColumn":3,"fix":{"range":[93,95],"text":"}"}}],"errorCount":5,"warningCount":4,"fixableErrorCount":2,"fixableWarningCount":4,"source":"function addOne(i) {\n if (i != NaN) {\n return i ++\n } else {\n return\n }\n};"}] <?xml version="1.0" encoding="utf-8"?> <testsuites> <testsuite package="org.eslint" time="0" tests="9" errors="9" name="/var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js"> <testcase time="0" name="org.eslint.no-unused-vars"><failure message="'addOne' is defined but never used."><![CDATA[line 1, col 10, Error - 'addOne' is defined but never used. (no-unused-vars)]]></failure></testcase> <testcase time="0" name="org.eslint.use-isnan"><failure message="Use the isNaN function to compare with NaN."><![CDATA[line 2, col 9, Error - Use the isNaN function to compare with NaN. (use-isnan)]]></failure></testcase> <testcase time="0" name="org.eslint.space-unary-ops"><failure message="Unexpected space before unary operator '++'."><![CDATA[line 3, col 16, Error - Unexpected space before unary operator '++'. (space-unary-ops)]]></failure></testcase> <testcase time="0" name="org.eslint.semi"><failure message="Missing semicolon."><![CDATA[line 3, col 20, Warning - Missing semicolon. (semi)]]></failure></testcase> <testcase time="0" name="org.eslint.no-else-return"><failure message="Unnecessary 'else' after 'return'."><![CDATA[line 4, col 12, Warning - Unnecessary 'else' after 'return'. (no-else-return)]]></failure></testcase> <testcase time="0" name="org.eslint.indent"><failure message="Expected indentation of 8 spaces but found 6."><![CDATA[line 5, col 1, Warning - Expected indentation of 8 spaces but found 6. (indent)]]></failure></testcase> <testcase time="0" name="org.eslint.consistent-return"><failure message="Function 'addOne' expected a return value."><![CDATA[line 5, col 7, Error - Function 'addOne' expected a return value. (consistent-return)]]></failure></testcase> <testcase time="0" name="org.eslint.semi"><failure message="Missing semicolon."><![CDATA[line 5, col 13, Warning - Missing semicolon. (semi)]]></failure></testcase> <testcase time="0" name="org.eslint.no-extra-semi"><failure message="Unnecessary semicolon."><![CDATA[line 7, col 2, Error - Unnecessary semicolon. (no-extra-semi)]]></failure></testcase> </testsuite> </testsuites>
/var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js 1:10 error 'addOne' is defined but never used no-unused-vars 2:9 error Use the isNaN function to compare with NaN use-isnan 3:16 error Unexpected space before unary operator '++' space-unary-ops 3:20 warning Missing semicolon semi 4:12 warning Unnecessary 'else' after 'return' no-else-return 5:1 warning Expected indentation of 8 spaces but found 6 indent 5:7 error Function 'addOne' expected a return value consistent-return 5:13 warning Missing semicolon semi 7:2 error Unnecessary semicolon no-extra-semi ✖ 9 problems (5 errors, 4 warnings) 2 errors, 4 warnings potentially fixable with the `--fix` option.
/var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js ║ Line │ Column │ Type │ Message │ Rule ID ║ ╟──────────┼──────────┼──────────┼────────────────────────────────────────────────────────┼──────────────────────╢ ║ 1 │ 10 │ error │ 'addOne' is defined but never used. │ no-unused-vars ║ ║ 2 │ 9 │ error │ Use the isNaN function to compare with NaN. │ use-isnan ║ ║ 3 │ 16 │ error │ Unexpected space before unary operator '++'. │ space-unary-ops ║ ║ 3 │ 20 │ warning │ Missing semicolon. │ semi ║ ║ 4 │ 12 │ warning │ Unnecessary 'else' after 'return'. │ no-else-return ║ ║ 5 │ 1 │ warning │ Expected indentation of 8 spaces but found 6. │ indent ║ ║ 5 │ 7 │ error │ Function 'addOne' expected a return value. │ consistent-return ║ ║ 5 │ 13 │ warning │ Missing semicolon. │ semi ║ ║ 7 │ 2 │ error │ Unnecessary semicolon. │ no-extra-semi ║ ╔════════════════════════════════════════════════════════════════════════════════════════════════════════════════╗ ║ 5 Errors ║ ╟────────────────────────────────────────────────────────────────────────────────────────────────────────────────╢ ║ 4 Warnings ║ ╚════════════════════════════════════════════════════════════════════════════════════════════════════════════════╝
TAP version 13
1..1
not ok 1 - /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js
---
message: '''addOne'' is defined but never used.'
severity: error
data:
line: 1
column: 10
ruleId: no-unused-vars
messages:
- message: Use the isNaN function to compare with NaN.
severity: error
data:
line: 2
column: 9
ruleId: use-isnan
- message: Unexpected space before unary operator '++'.
severity: error
data:
line: 3
column: 16
ruleId: space-unary-ops
- message: Missing semicolon.
severity: warning
data:
line: 3
column: 20
ruleId: semi
- message: Unnecessary 'else' after 'return'.
severity: warning
data:
line: 4
column: 12
ruleId: no-else-return
- message: Expected indentation of 8 spaces but found 6.
severity: warning
data:
line: 5
column: 1
ruleId: indent
- message: Function 'addOne' expected a return value.
severity: error
data:
line: 5
column: 7
ruleId: consistent-return
- message: Missing semicolon.
severity: warning
data:
line: 5
column: 13
ruleId: semi
- message: Unnecessary semicolon.
severity: error
data:
line: 7
column: 2
ruleId: no-extra-semi
... /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:1:10: 'addOne' is defined but never used. [Error/no-unused-vars] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:2:9: Use the isNaN function to compare with NaN. [Error/use-isnan] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:3:16: Unexpected space before unary operator '++'. [Error/space-unary-ops] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:3:20: Missing semicolon. [Warning/semi] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:4:12: Unnecessary 'else' after 'return'. [Warning/no-else-return] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:5:1: Expected indentation of 8 spaces but found 6. [Warning/indent] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:5:7: Function 'addOne' expected a return value. [Error/consistent-return] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:5:13: Missing semicolon. [Warning/semi] /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js:7:2: Unnecessary semicolon. [Error/no-extra-semi] 9 problems
/var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(1,10): error no-unused-vars : 'addOne' is defined but never used. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(2,9): error use-isnan : Use the isNaN function to compare with NaN. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(3,16): error space-unary-ops : Unexpected space before unary operator '++'. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(3,20): warning semi : Missing semicolon. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(4,12): warning no-else-return : Unnecessary 'else' after 'return'. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(5,1): warning indent : Expected indentation of 8 spaces but found 6. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(5,7): error consistent-return : Function 'addOne' expected a return value. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(5,13): warning semi : Missing semicolon. /var/lib/jenkins/workspace/Releases/ESLint Release/eslint/fullOfProblems.js(7,2): error no-extra-semi : Unnecessary semicolon. 9 problems
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Licensed under the MIT License.
https://eslint.org/docs/user-guide/formatters