Always put {} around code blocks even though they're not technically required.  It's less error prone, and code is easier to read when it's consistently formatted, not 95% one way and 5% something else.
Also almost always put statements on a newline, like this:
if (!json || !json.response) {
    return;
}

The only exception I make is when not doing so makes it significantly easier to read, for example if you have a bunch of similar if statements in a row with short bodies.