JSFiddle - React, Tailwind, and code Playground

JavaScript

function fixedLength(str, len, bol) {
    if(str.length <= length) {
       return str;   
    }
    
    var rtn = str.substr(0, len).match(/.* /);
    if(rtn == null) {
        rtn = "";
    } else {
        rtn = rtn + "...";
    }
    return rtn;
}

var str = "the quick brown fox jumped over the lazy dog";

for (var i = 0; i < 45; i++) {
    document.write("i:" + i + " - " + fixedLength(str, i) + "<br>");
}