![Set a breakpoint based on a certain condition.](/static/blog/set-a-breakpoint-based-on-a-certain-condition/image/set-breakpoint-based-a-d83a98122329b.gif)
When you set a breakpoint, you can make it conditional based on the result of an expression. Right click on the line gutter and select Add Conditional Breakpoint and enter your expression.
If you have a callback like:
function callback(result, err) {
//set a conditional breakpoint based on the existence of err
}
You could set a conditional breakpoint based on the existence of err
.