To mock a response in javascript use JSON to specify the details with the following format:

"httpResponse": {
    "statusCode": 200,
    "body": "",
    "cookies": [],
    "headers": [],
    "delay": {
        "timeUnit": "MICROSECONDS",
        "value": 0
    }
}

Each cookie or header array entry has the following syntax:

{
    "name": "someName",
    "values": ["someValueOne", "someValueTwo", ...]
}

The "timeUnit" value in "delay" can be:

"NANOSECONDS"
"MICROSECONDS"
"MILLISECONDS"
"SECONDS"
"MINUTES"
"HOURS"
"DAYS"

The same example as above would be:

"httpResponse": {
    "statusCode": 401,
    "headers": [
        {
            "name": "Content-Type",
            "values": ["application/json; charset=utf-8"]
        },
        {
            "name": "Cache-Control",
            "values": ["public, max-age=86400"]
        }
    ],
    "body": JSON.stringify({ message: "incorrect username and password combination" }),
    "delay": {
        "timeUnit": "SECONDS",
        "value": 1
    }
}