Gulp Jscs - TypeError: Cannot convert undefined or null to object

Question

I wanted to use gulp-jscs in my project, so I've installed it according the documentation:

npm install --save-dev gulp-jscs

But when I try to run the gulp file, I'm getting this error:

TypeError: Cannot convert undefined or null to object
    at Function.keys (native)
    at copyConfiguration (C:\Users\[User]\Desktop\[Project]\
    node_modules\jscs\lib\config\configuration.js:920:12)

Also, there are other errors related to this:

at NodeConfiguration.Configuration.
_processConfig([location-path]\node_modules\jscs\lib\config\configuration.js:459:5)
    at NodeConfiguration.Configuration.load 
([location-path]\node_modules\jscs\lib\config\configuration.js:211:10)
    at null.StringChecker.configure 
([location-path]\node_modules\jscs\lib\string-checker.js:62:29)
    at null.Checker.configure ([location-path]\node_modules\jscs\lib\checker.js:27:39)
    at Object.module.exports ([location-path]\node_modules\gulp-jscs\index.js:35:10)
    at Gulp.<anonymous> ([location-path]\Gulpfile.js:60:17)
    at module.exports ([location-path]\node_modules\orchestrator\lib\runTask.js:34:7)
    at Gulp.Orchestrator._runTask ([location-path]\node_modules\orchestrator\index.js:273:3)
Process terminated with code 1.

Answer 1

You need to have a .jscsrc file in the root of you project present. In there you can provide options for JSCS as well as the code style rules that should be followed.

Below is the .jscsrc that's used by node-jscs project itself. You can use this to base your own configuration on.

{
    "preset": "google",
    "fileExtensions": [".js", "jscs"],

    "requireSemicolons": true,
    "requireParenthesesAroundIIFE": true,
    "maximumLineLength": 120,
    "validateLineBreaks": "LF",
    "validateIndentation": 4,
    "disallowTrailingComma": true,
    "disallowUnusedParams": true,

    "disallowSpacesInsideObjectBrackets": null,
    "disallowImplicitTypeConversion": ["string"],

    "safeContextKeyword": "_this",

    "jsDoc": {
        "checkAnnotations": "closurecompiler",
        "checkParamNames": true,
        "requireParamTypes": true,
        "checkRedundantParams": true,
        "checkReturnTypes": true,
        "checkRedundantReturns": true,
        "requireReturnTypes": true,
        "checkTypes": "capitalizedNativeCase",
        "checkRedundantAccess": true,
        "requireNewlineAfterDescription": true
    },

    "excludeFiles": [
        "test/data/**",
        "patterns/*"
    ]
}

Note that jscs won't actually check for anything unless you have a "preset" in your .jscsrc or have explicitly specified the rules that should be followed.