JSFiddle - React, Tailwind, and code Playground

by Lindow

HTML

<div id="Test">
  abcdefghijklmn, opqrstuvwxyzAB
  ddoafkpdsfk, 
  dsapdlasèd. CDEFGHIJKLMNO,
  dofkdspakdasadsadsdsak, PQRSTUVWXYZ
</div>

CSS

#Test {
  font-family: courrier;
  position: absolute;
  height: auto;
  width: auto;
  white-space: wrap;
  overflow: auto;
  font-size:150%;
}

JavaScript

function longestWord(string) {
    var str = string.split(" ");
    var longest = [];
    var $word = $('<span style="visibility: hidden;">').appendTo(document.getElementById('Test'));
    var width = 0;
    
    for (var i = 0; i < str.length; i++) {
        width = $word.text(str[i]).width() || 0;
        longest = longest > width ? longest : width;
    }
    
    $word.remove();
    
    return longest;
}

var test = document.getElementById("Test");
var longest_word = longestWord(test.innerHTML);
alert(longest_word);