Read text file line by line and use data for input

Question

I am reading in a text file where I know what each line of the file is.

For example, the first line is a starting coordinate pair that is in the format {"x":9,"y":9} and the second line is a end coordinate pair.

There exists global variable var startCoord = {"x": startX, "y": startY};

How can I pull the x and y from the file to set as the new startCoord.x and startCoord.y respectively?

JSFiddle here

Example of text file:

{"x":9,"y":9}
{"x":4,"y":104}
{"x":124,"y":51}
{"x":92,"y":65}
{"x":113,"y":31}

Phil · Accepted Answer · 2017-02-06 05:11:20Z

1

You need to parse the JSON in each line into an object in order to access properties like x and y. To do so, simply change

var obj = lines[0] // or whatever index you want to parse

to

var obj = JSON.parse(lines[0])

https://jsfiddle.net/8h3u2vxd/1/

I would also optimise your for loop like so

const lines = this.result.split('\n');
if (lines.length > 0 && lines.length % 2 > 0) {
  throw 'Invalid data format'
}
for (let i = 0, l = lines.length; i < l; i += 2) {
  let startObj = JSON.parse(lines[i])
  let endObj = JSON.parse(lines[i + 1])
  // and so on  
}

https://jsfiddle.net/8h3u2vxd/2/

edited Feb 6, 2017 at 5:11

answered Feb 6, 2017 at 4:59

Phil

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