JSFiddle - React, Tailwind, and code Playground
HTML
<button><input type="file"> nene</button>JavaScript
//input = DOMnode('input')
//type=file
input.onchange = ()=> {
let reader = new FileReader();
reader.readAsText(input.files[0]);
reader.onload = () => console.log( reader.result.split('\n').reduce((res,el,i)=>~el.indexOf('word') ? [...res,i+1] : res, []) );
}