JavaScript中const、var、let定义变量的区别

function fun(){
        	var a=5;
        	console.log(a);
 }

		
hahah1
		
hahah2
		
hahah3
		
hahah4

var li =document.getElementById('p').getElementsByTagName('li');
        for(var i = 0; i < li.length; i++) {            
            li[i].onclick =function(event) {
                console.log('li : '+i+'  '+this.innerHTML);
            }
        }

var li =document.getElementById('p').getElementsByTagName('li');
        for(let i = 0; i < li.length; i++) {            
            li[i].onclick =function(event) {
                console.log('li : '+i+'  '+this.innerHTML);
            }
        }