JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="editor" cols="30" rows="10">console.log('hello world')
some text
zzz "quotes in 'quotes' here" fff
escaped quote doesn\'t counts
</textarea>
<pre id="display"></pre>

CSS

#editor {
  width: 100%;
  height: 50vh;
  background: white;
}

JavaScript

function analyzeThis(){
  var quotedRanges = [], str = editor.value, inQutes = false, prev = ' ', char, quote, range;
  
  for (let i = 0; i<str.length; i++) {
  	char = str[i]
    if (!inQutes && char.match(/['"]/) && prev !== '\\') {
    	inQutes = true
      quote = char
      range = [i]
    } else if (inQutes && char === quote  && prev !== '\\') {
    	inQutes = false
      range.push(i)
      quotedRanges.push(range)
    }
    prev = char
  }
  
  displayRanges(quotedRanges)
}

analyzeThis()
editor.oninput = analyzeThis

function displayRanges(quotedRanges){
	display.innerHTML = quotedRanges.map(range => {
  	let [start,end] = range
    return range.toString() + ' # ' + editor.value.slice(start+1, end) + '\n'
  }).join('')
}