Add an event listener to some changing property and then change the font size accordingly.
document.getElementById("testInput").addEventListener("keyup", function(){
var inputText = document.getElementById("testInput").value; document.getElementById("test").innerHTML = inputText;
if(inputText.length > 10){
document.getElementById("test").style.fontSize = "8px";
}else if(inputText.length > 5){
document.getElementById("test").style.fontSize = "10px";
}else{
document.getElementById("test").style.fontSize = "12px";
}
});
<input id="testInput">
<div id="test"></div>
1
solved Setting min and max font size for a fixed-width text div that accepts variable text [closed]