js-code-start

Find js code start point, skip any whitespace and comments.

When you want to place some code at beginning of JS file, you don't want to messup "use strict" block, so this module help find the first real code beginning, thus skip any whitespace, comments, and "use strict" block.

Usage

const findStart = require('js-code-start')
var code = `
// line comment
// line comment
/*
Block comment
*/

'use strict';

console.log('code start');
`
console.log(findStart(code))

The result is

{ start: 67,
  line: 8,
  col: 13,
  strict: true,
  ast: 
   [ { type: 1, start: 0, end: 0 },
     { type: 2, start: 1, end: 16 },
     { type: 2, start: 17, end: 32 },
     { type: 3, start: 33, end: 51 },
     { type: 1, start: 52, end: 53 },
     { type: 4, start: 54, end: 66 } ] }

And the js code start point is 67(after first ; char), in strict mode.

Note

The line number start from 1, but the column number start from 0, this is follow the Emacs convention.