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ExpressionEvaluator

Evaluator for expression, that starts with "=" like "=2+2".

const instance = new ExpressionEvaluator();
const result = instance.exec("=2+2");
// result == "4"

or with tryExec

const instance = new ExpressionEvaluator();
const result = instance.tryExec("=2+2");
// result == { success: true, value: "4" }

Constructors​

Constructor​

new ExpressionEvaluator(): ExpressionEvaluator

Returns​

ExpressionEvaluator

Properties​

ACTIVATOR​

static ACTIVATOR: string

Methods​

addEvaluator()​

addEvaluator(evaluate): void

Add your own instance evaluator.

const instance = new ExpressionEvaluator();
instance.addEvaluator((input) => {
    return input.replace("%myVariable%", "Chuck Norris");
});
const greetings = instance.exec("=Hello %myVariable%");
// greetings == "Hello Chuck Norris"

const otherInstance = new ExpressionEvaluator();
const greetings = otherInstance.exec("=Hello %myVariable%");
// greetings == "Hello %myVariable%"

Parameters​

evaluate​

EvaluateFunc

Function that takes one input string and should return string

Returns​

void

validate()​

validate(input): boolean

This function checks if the input is valid and startsWith the activator.

Parameters​

input​

string

the input to validate

Returns​

boolean

true if successful validated, otherwise false

tryExec()​

tryExec(input): ExpressionEvaluatorResult

Tries to Evaluate the input by known evaluators and returns a object.

const instance = new ExpressionEvaluator();
const result = instance.tryExec("=2+2");
// result == { success: true, value: "4" }
const instance = new ExpressionEvaluator();
const result = instance.tryExec("blub");
// result == { success: false, value: null, error: "input does not starts with "="" }

Parameters​

input​

string

Returns​

ExpressionEvaluatorResult

exec()​

exec(input): string

Evaluate the input by known evaluators. Caution, this will throw an error if evaluation fails.

const instance = new ExpressionEvaluator();
const result = instance.exec("=2+2");
// result == "4"

this will throw

const instance = new ExpressionEvaluator();
const result = instance.exec("2+2");
// error input does not starts with "="

Parameters​

input​

string

Returns​

string

addGlobalEvaluator()​

static addGlobalEvaluator(evaluate): void

Add your own global evaluator. Note: Adding a global evaluator will triggered in every instance! If you don't want to trigger globally, use addEvaluator in the instance.

ExpressionEvaluator.addEvaluator((input) => {
    return input.replace("%myVariable%", "Chuck Norris");
});
const instance = new ExpressionEvaluator();
const greetings = instance.exec("=Hello %myVariable%");
// greetings == "Hello Chuck Norris"

Parameters​

evaluate​

EvaluateFunc

Function that takes one input string and should return string

Returns​

void