disallowTrailingComma does not work in jscs

Question

I am using http://jscs.info. I need to get a warning if my app has left trailing comma, example, using:

var x = {
    prop1: 10,
    prop2: 20,
};

I should get a warning. With the following settings:

disallowTrailingComma true
requireTrailingComma true

I cannot get the warning.

What I am doing wrong here?

{
    "disallowCommaBeforeLineBreak": null,
    "disallowDanglingUnderscores": true,
    "disallowEmptyBlocks": true,
    "disallowImplicitTypeConversion": [ "string" ],
    "disallowKeywordsOnNewLine": [ "else" ],
    "disallowKeywords": [ "with" ],
    "disallowMixedSpacesAndTabs": true,
    "disallowMultipleLineBreaks": true,
    "disallowMultipleLineStrings": true,
    "disallowMultipleVarDecl": null,
    "disallowPaddingNewlinesInBlocks": null,
    "disallowQuotedKeysInObjects": true,
    "disallowSpaceAfterBinaryOperators": true,
    "disallowSpaceAfterKeywords": [ "for", "while", "do", "switch" ],
    "disallowSpaceAfterLineComment": false,
    "disallowSpaceAfterObjectKeys": null,
    "disallowSpaceAfterPrefixUnaryOperators": true,
    "disallowSpaceBeforeBinaryOperators": null,
    "disallowSpaceBeforeBlockStatements": null,
    "disallowSpaceBeforePostfixUnaryOperators": true,
    "disallowSpacesInAnonymousFunctionExpression": {
        "beforeOpeningCurlyBrace": true
    },
    "disallowSpacesInConditionalExpression": null,
    "disallowSpacesInFunctionDeclaration": null,
    "disallowSpacesInFunctionExpression": {
        "beforeOpeningRoundBrace": true
    },
    "disallowSpacesInNamedFunctionExpression": null,
    "disallowSpacesInsideArrayBrackets": null,
    "disallowSpacesInsideObjectBrackets": null,
    "disallowSpacesInsideParentheses": null,
    "disallowTrailingComma": true, // -------------------null
    "disallowTrailingWhitespace": true,
    "disallowYodaConditions": true,
    "maximumLineLength": 120,
    "requireAlignedObjectValues": "skipWithFunction",
    "requireBlocksOnNewline": true,
    "requireCamelCaseOrUpperCaseIdentifiers": "ignoreProperties",
    "requireCapitalizedConstructors": true,
    "requireCommaBeforeLineBreak": true,
    "requireCurlyBraces": [ "if", "else", "for", "while", "do", "try", "catch" ],
    "requireDotNotation": true,
    "requireKeywordsOnNewLine": null,
    "requireLineFeedAtFileEnd": true,
    "requireMultipleVarDecl": true,
    "requireOperatorBeforeLineBreak": true,
    "requirePaddingNewlinesInBlocks": true,
    "requireParenthesesAroundIIFE": true,
    "requireSpaceAfterBinaryOperators": null,
    "requireSpaceAfterKeywords": [ "if", "else", "return", "try", "catch" ],
    "requireSpaceAfterLineComment": null,
    "requireSpaceAfterObjectKeys": true,
    "requireSpaceAfterPrefixUnaryOperators": null,
    "requireSpaceBeforeBinaryOperators": true,
    "requireSpaceBeforeBlockStatements": true,
    "requireSpaceBeforePostfixUnaryOperators": null,
    "requireSpacesInAnonymousFunctionExpression": {
        "beforeOpeningRoundBrace": true
    },
    "requireSpacesInConditionalExpression": true,
    "requireSpacesInFunctionDeclaration": {
        "beforeOpeningRoundBrace": true,
        "beforeOpeningCurlyBrace": true
    },
    "requireSpacesInFunctionExpression": {
        "beforeOpeningCurlyBrace": true
    },
    "requireSpacesInNamedFunctionExpression": {
        "beforeOpeningRoundBrace": true,
        "beforeOpeningCurlyBrace": true
    },
    "requireSpacesInsideArrayBrackets": "all",
    "requireSpacesInsideObjectBrackets": "allButNested",
    "requireSpacesInsideParentheses": "all",
    "requireTrailingComma": true, // -------------------------true
    "safeContextKeyword": true,
    "validateIndentation": 4,
    "validateJSDoc": {
        "checkParamNames": true,
        "requireParamTypes": true
    },
    "validateLineBreaks": "LF",
    "validateQuoteMarks": true
}

Answer 1

Your two options contradict each other. At the same time you require that there are trailing commas with "requireTrailingComma": true and forbid the trailing comma with "disallowTrailingComma": true.

To get the warning for trailing commas, remove the "requireTrailingComma": true option and at the same time keep "disallowTrailingComma": true.

---

UPDATE

I removed the following options that generated errors in console and it worked for your slightly modified example code, that only the trailing comma warning is displayed:

var x ={
    prop1 : 10,
    prop2 : 20,
};

I removed the following lines (shown together with their errors)

"disallowSpaceAfterLineComment": false

because of

AssertionError: disallowSpaceAfterLineComment option requires the value true

and

"safeContextKeyword": true

because

AssertionError: safeContextKeyword option requires string or array value

and

"requireTrailingComma": true

because of the contradiction described above.