How to use Javascript to read local text file and read line by line?

Question

I have a web page made by html+javascript which is demo, I want to know how to read a local csv file and read line by line so that I can extract data from the csv file.

Answer 1

Without jQuery:

document.getElementById('file').onchange = function(){    var file = this.files[0];    var reader = new FileReader();   reader.onload = function(progressEvent){     // Entire file     console.log(this.result);      // By lines     var lines = this.result.split('\n');     for(var line = 0; line < lines.length; line++){       console.log(lines[line]);     }   };   reader.readAsText(file); }; 

HTML:

<input type="file" name="file" id="file"> 

Remember to put your javascript code after the file field is rendered.

Answer 2

Using ES6 the javascript becomes a little cleaner

handleFiles(input) {      const file = input.target.files[0];     const reader = new FileReader();      reader.onload = (event) => {         const file = event.target.result;         const allLines = file.split(/\r\n|\n/);         // Reading line by line         allLines.forEach((line) => {             console.log(line);         });     };      reader.onerror = (event) => {         alert(event.target.error.name);     };      reader.readAsText(file); }