how to read file and send to API javascript code example

Example 1: how to load localt ext file in js

const fileUrl = '' // provide file location

fetch(fileUrl)
   .then( r => r.text() )
   .then( t => console.log(t) )

Example 2: javascript read file lines into array vanilla

const fileList = event.target.files;
let fileContent = "";

const fr = new FileReader();
fr.onload = () => {
  fileContent = fr.result;
  console.log('Commands', fileContent);
}

fr.readAsText(fileList[0]);