Diamond Pattern in Javascript

// Diamond Pattern in Javascript......

function Diamond(n){
let str=''
for(let i=0;i<(n2)-1;i++){
for(let j=0;j<(n2)-1;j++){
if((j>=n-1-i&&j<=n-1+i &&i<n )||(i>=n &&j>i-n && j<(n3)-2-i) ){
str+=''
}else{
str+=' '
}

}
str+='\n'

}
return str
}
console.log(Diamond(8))