the js code is as follows:
function Stack(){
let items = [];
//
this.push = function(element) {
items.push(element);
}
this.pop = function(){
return items.pop();
}
//
this.peek = function(){
return items[items.length-1];
}
this.isEmpty = function(){
return items.length == 0;
}
this.size = function(){
return items.length;
}
this.clear = function(){
items = [];
}
this.print = function(){
console.log(items.toString());
}
}
let st = new Stack();
console.log(st.isEmpty());
st.push(1);
st.push(2);
st.push(3);
console.log(st.peek());
console.log(st.isEmpty());
console.log(st.print());
st.pop();
console.log(st.print()); the output result is
true
3
false
1
undefined
1
undefined