@liquidform/formula-lang v0.0.9

An expression parser and executor for LiquidForm's formula language

LiquidForm's expressions are a subset of JavaScript expression syntax.

They're used for field validation, computed fields and text templates.

Literals

• numbers: 2, -3.6
• strings: 'single quoted', "double quoted"
• booleans: true, false

Identifiers

The lang supports identifiers and property chains. Bracket notation is also supported.

Identifiers are resolved from the context.properties object passed to the evaluateExpression(expression:String, context:Context):any method.

Examples

person.addresses[0].street

listOfOptions[selectedOptionId].label

Functions

Functions can be called to compute values. They must be present in the context.functions object passed to the evaluateExpression(expression:String, context:Context):any method.

Examples

evaluateExpression(
    'Math.max(valueA, valueB)', 
    {
        functions : {Math},
        properties : {
            valueA : 12,
            valueB : 13
        }
    });

Arithmetics

• * multiplication: 2 * 3 * 22
• / division: 81 / 9
• + addition: 2 + 2
• - subtraction 7 -2
• % modulus 5 % 2

Comparison

• == strict equality
• != strict inequality
• > greater than
• < less than
• >= equal or greater than
• <= equal or less than

Logical

• && logical and
• || logical or

Ternary operator

//syntax
condition ? trueResult : falseResult

//example
carMakeField == 'Tesla' ? 'electric' : 'petrol'

Unary operator

 !false //== true 

The undefined value

The syntax tries to steer away from undefined and throws a ParseError when it encounters one.