Statements and control flow

The statements a script body can contain, including if/else and return.

A script body is a sequence of statements that run from top to bottom. These are the available statements:

Statement	Example
Variable declaration	var count = 0, const limit = 10
Resource binding	const weather: com.example.Weather
Assignment	count = 1, obj.prop = 2, list[0] = 3
Expression statement	audit.log(message: "started")
if / else if / else	See below
return	return total

An expression statement evaluates an expression and discards the result. It’s mainly useful for calling a resource function for its side effect.

There are no loops and no user-defined functions.

if statements

An if statement runs its body only when its condition is true. The condition must be in parentheses and the body in curly braces.

request Check {
    const amount = 120
    if (amount > 100) {
        return "large"
    }
    return "small"
}

Add else if branches to test more conditions in order, and an else branch to run when no condition matched:

contract grades.Letter(score: int32, late: boolean) {
    if (score >= 90 && !late) {
        return "A"
    } else if (score >= 80) {
        return "B"
    } else {
        return "C"
    }
}

• The condition must evaluate to a boolean. if (1) or if (name) is an error: write if (name != null) instead.
• Curly braces are always required, even for a single statement.
• Each body is its own scope.

return

return ends the script immediately. Its value becomes the returnValue of the response, and any statements after it are skipped.

request EarlyReturn {
    const user = { name: null }
    if (user.name == null) {
        return "anonymous"
    }
    return user.name
}

A script returns null if it uses a bare return or reaches the end of its body without a return.

The returned value must start on the same line as return. A value on the next line isn’t part of the return, so the script returns null.