JS API Error message should contain `index` position

[futurist]

When using JS API, code as below:

standard.lintText('var a = 1\n1var b=2;', {fix: true}, (err, result)=>{
	console.log(err, result)
})

the error object of callback result

null { filePath: '<text>',
  messages:
   [ { ruleId: null,
       fatal: true,
       severity: 2,
       source: 'var a = 1\n1var b=2;',
       message: 'Parsing error: Identifier directly after number',
       line: 2,
       column: 2 } ],
  errorCount: 1,
  warningCount: 0,
  source: 'var a = 1\n1var b=2;' }

There's should add aditional index: 12 in the above result, for better locating the error.

This will good for editors like Emacs, to goto-char in source position instead of line+column combination.

[feross]

We're currently just returning the object that ESLint provides. If you want that additional information, you can read in the file and calculate the index yourself.

[futurist]

That's ok, for anyone encountered the same problem, I've created a tool for adding index field:

https://github.com/futurist/src-location