How to loop through a .txt file and get the values in javascript

Question

Basically I have my code set up like this:

function converttxttoArray( filename )
{
    var reader = (window.XMLHttpRequest != null ) 
               ? new XMLHttpRequest() 
               : new ActiveXObject("Microsoft.XMLHTTP");
    reader.open("GET", filename, false );
    reader.send( );
    return reader.responseText.split(/(\r\n|\n)/g); 
}
var stop_list = converttxttoArray("../data/stops.txt");

  var text = "";
  var i;
  for (i = 0; i < stop_list.length; i++) {
      text += stop_list[i] + "<br>";
  }

console.log(text) will just give me:

 stop_id,stop_code,stop_name,stop_lat,stop_lon,zone_id,stop_url,location_type,parent_station,platform_code,wheelchair_boarding

70011,70011,San Francisco Caltrain,37.77639,-122.394992,1,http://www.caltrain.com/stations/sanfranciscostation.html,0,ctsf,NB,1

70012,70012,San Francisco Caltrain,37.776348,-122.394935,1,http://www.caltrain.com/stations/sanfranciscostation.html,0,ctsf,SB,1 

And here is how the content in my stop.txt file look like:

stop_id,stop_code,stop_name,stop_lat,stop_lon,zone_id,stop_url,location_type,parent_station,platform_code,wheelchair_boarding
70011,70011,San Francisco Caltrain,37.77639,-122.394992,1,http://www.caltrain.com/stations/sanfranciscostation.html,0,ctsf,NB,1
70012,70012,San Francisco Caltrain,37.776348,-122.394935,1,http://www.caltrain.com/stations/sanfranciscostation.html,0,ctsf,SB,1
70021,70021,22nd St Caltrain,37.757599,-122.39188,1,http://www.caltrain.com/stations/22ndstreetstation.html,0,ct22,NB,2
70022,70022,22nd St Caltrain,37.757583,-122.392404,1,http://www.caltrain.com/stations/22ndstreetstation.html,0,ct22,SB,2
70031,70031,Bayshore Caltrain,37.709537,-122.401586,1,http://www.caltrain.com/stations/bayshorestation.html,0,ctba,NB,1
70032,70032,Bayshore Caltrain,37.709544,-122.40198,1,http://www.caltrain.com/stations/bayshorestation.html,0,ctba,SB,1
70041,70041,So. San Francisco Caltrain Station,37.65589,-122.40487,1,http://www.caltrain.com/stations/southsanfranciscostation.html,0,ctssf,NB,2
70042,70042,So. San Francisco Caltrain Station,37.655946,-122.405018,1,http://www.caltrain.com/stations/southsanfranciscostation.html,0,ctssf,SB,2
70051,70051,San Bruno Caltrain,37.631128,-122.411968,1,http://www.caltrain.com/stations/sanbrunostation.html,0,ctsb,NB,1

This file is in the cvs style. What I want is to get the stop_name, stop_id, stop_code, stop_long.... of each item in the array.

Using javascript Promise api would be great

Answer 1

You can use RegExp /\n+/ at converttxttoArray; Array.prototype.shift() to remove, store first item of stop_list array ;.split() with RegExp /,/ to convert string to an array; retrieve index of "stop_name" within removed first item within stop_list using .indexOf(); Array.prototype.map() ,.split() with /,/ as parameter to return item at index of "stop_name" within remainder of stop_list

window.onload = function() {

  function converttxttoArray(filename) {
    var reader = (window.XMLHttpRequest != null) 
                 ? new XMLHttpRequest() 
                 : new ActiveXObject("Microsoft.XMLHTTP");
    reader.open("GET", filename, false);
    reader.onload = function() {

      var stop_list = this.responseText.split(/\n+/);
      var re = /,/;
      var headers = stop_list.shift().split(re);
      var index = headers.indexOf("stop_name");
      var res = stop_list.map(function(val, key) {
        return val.split(re)[index];
      });
      console.log(res);

      var text = "";
      var i;
      for (i = 0; i < stop_list.length; i++) {
        text += res[i] + "<br>";
      }
      console.log(text);
      document.body.innerHTML = text;

    }
    reader.send();

  }
  converttxttoArray("stops.txt");

}

plnkr http://plnkr.co/edit/dhr6hQAb151c8oFBTvqk?p=preview