打印三角形

````javascript
function shape(){
    for(var i=-3; i<=3; i++){
        for(var n=-3; n<3; n++){
            if(Math.abs(i)+Math.abs(n)<=3){
                document.write('*')
            }else{
                document.write("&nbsp")
            }
        }
        document.write('<br>')
    }
}
shape()
````