<input type="text" id="woba"></input><button onclick="funkcija()">Spausk</button>

<p id="du"></p>



<input type="range" max="20" id="rangas"></input>



<script>
function funkcija(){
var rang = document.getElementById("rangas").value;
var op = document.getElementById("woba").value;
var ilg = op.length;
var m = rang;
console.log(rang);
if(ilg>m){
var k = op.substring(0,m);
var div = document.getElementById("du");


div.innerHTML=k;

console.log(ilg);
}
else{
var div = document.getElementById("du");


div.innerHTML=op;

console.log(ilg);

}
}

</script>