function jia(a,b){
return a+b;
}
function jian(a,b){
return a-b;
}
function cheng(a,b){
return a*b;
}
function chu(a,b){
return a/b;
}
var a=4;b=2;
var jia=jia(a,b);
var jian=jian(a,b);
var cheng=cheng(a,b);
var chu=chu(a,b);
// 结果
alert("加:"+jia+"减:"+jian+"乘:"+cheng+"除:"+chu);