SOURCE

let output = "";
for(let i = 0; i < 4; i++ ) {
    for(let k = 1; k < 4 - i; k++) 
    {
        output += "\xa0";
    } 
    for(let j = 1; j <= 2 * i + 1; j++) {
        output += "*"
    }
    console.log(output);
    output = "";
}

for(let i = 3; i > 0; i-- ) {
    for(let k = 1; k <= 4 - i; k++) 
    {
        output += "\xa0";
    } 
    for(let j = 1; j <= 2 * i - 1; j++) {
        output += "*"
    }
    console.log(output);
    output = "";
}

	<script src = ./1.js></script>