function myF(){

            // let str = "Welcome to JS world";

            // let x = str.search("JS");

            let x =document.getElementById('demo').innerHTML.search("JS");

​

            document.getElementById('demo3').innerHTML = "Welcome to JS world的JS在第"+ x + "個起始位置";

        }

​

        function myF2(){

            // let str =document.getElementById('demo2').innerHTML;

            // let txt = str.replace("college","ELP");

            let txt = document.getElementById('demo2').innerHTML.replace("college","ELP");

​

            document.getElementById('demo2').innerHTML = txt;

​

        }