Run results for: reading textbox: textContent vs substringData

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:73.0) Gecko/20100101 Firefox/73.0

Browser: Firefox 73

Operating system: Windows 7

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
data.slice	84155.0 Ops/sec
substringData	2058751.0 Ops/sec
textContent.slice	83598.7 Ops/sec

Script Preparation code:

var xs = [...Array(1000).keys()].map(i => {
  var textbox = document.createElement(`div`);
  textbox.contentEditable = true;
  textbox.textContent = [...Array(10000).keys()].map(n => String.fromCharCode(((n+i) % 10) + 65)).join(``);
  return textbox;
});

var t = 0;

Tests:

data.slice
let textbox = xs[(Math.random()*1000)|0]; let i = (Math.random()*9000)|0; let s = textbox.firstChild.data.slice(i, i+100); t += 0|(s.length + s.charCodeAt((Math.random()*100)|0));
substringData
let textbox = xs[(Math.random()*1000)|0]; let i = (Math.random()*9000)|0; let s = textbox.firstChild.substringData(i, 100); t += 0|(s.length + s.charCodeAt((Math.random()*100)|0));
textContent.slice
let textbox = xs[(Math.random()*1000)|0]; let i = (Math.random()*9000)|0; let s = textbox.textContent.slice(i, i+100); t += 0|(s.length + s.charCodeAt((Math.random()*100)|0));

Run results for: reading textbox: textContent vs substringData

data.slice

substringData

textContent.slice