var i = 10;
var a = i++;        // i = i + 1;
alert(a);

alert ( 10 > 5 );        
var i = 100;
var n = 100;
alert(i == n);    
alert(i != n);
alert(i === n) 

var i = 8;     //outputs false
alert ( i<5 && i<10);        //outputs true
alert(!(10 > 5));            //outputs false

if(condition) statements1 else statement2

if(10 > 5) {
        alert(“hello world”);
    }
    
    var i = 90;
    if(i > 100) {
        alert(i + “大于100”);
    }else if(i > 80) {
         alert(i + “大于80”); 
    }else{
         alert(i + “小于100”); 
    }

switch (expression){
        case value:
            //statement
            break;
        case value:
            //statement
            break;
        default:
            //statement
    }

 var i = 25;
    switch(i){
        case 25:
            alert(i + "等于 25");
            break;
        case 100:
            alert(100);
            break;
        default:
            alert(‘other’);
 }