Templates and Expressions

Templates

A template is a string literal that contains zero or more substitutions, where a substitution is a script or expression embedded inside { and }.

The way that we interpret a template inside of an expression or script is by placing the template between characters, also called a template string:

`The result of 1 + 1 is ${1 + 1}.`

Expressions

An expression is a value composed, recursively, of one or more values, joined by a combination of operators and parenthesized subexpressions.

add(1, (i < 2 ? 1 : i)) + "x"

Expressions may be used to construct Adaptive Script statements and may be also used directly by Adaptive Framework when a value needs to be computed.

Before moving onto Statements, it's worth noting that Expressions are quite capable of being used to compute some complicated logic by nesting expressions in a functional-looking manner. For example, take the following expression:

add( if(1 < 2, 1, 2), 3 )

This expression says to add 1 to 3 if 1 is less than 2, and to add 2 to 3 otherwise. A more readable way to express this logic is using the syntactic sugar provided by statements.

Values

Values are the fundamental components of an expression. They can be List Values, Object Values, Scalar Literals, Evaluations, Parenthesized Expressions or Template Strings.

42
"abc"
true
null
[1, 2, 3]
{ "x": 42, "y": "abc" }
(1 + 1) + 3
`1 + 1 is {1 + 1}`

Factors

Factors join values with zero or more mathematical operators, optionally separated with parentheses. This includes multiplication *, division /, addition +, subtraction -, exponentiation **, modulus % and unary negation -.

Comparisons

Comparisons join factors with zero or more relational operators, optionally separated with parentheses. This includes less than <, less than or equal to <=, greater than >, greater than or equal to >=, equal ==, not equal !=, strict equal === and not strict equal !==. Comparisons result in a boolean result when evaluated.

42 < 2
2 >= 2
1 !== 0
a === b

Logical Expressions

Logical Expressions are expressions joined together by the logical operators && (and), || (or), and ! (not).

(a || b) && (c || !d)

Nullish Coalescing

A Nullish Coalescing expression joins two Logical Expressions using the ?? operator. The result is the first expression if it is not null or undefined, otherwise the result is the second expression.

a ?? b