Sandboxed javascript expressions

Allows evaluating untrusted javascript expressions in a nodejs server and in browsers

Usage

// Expressions are compiled to a function for optimum performance.
let expression = compileJsExpression('Math.atan(deltaX / deltaY) * 180 / Math.PI'); // calculate angle

// Here we specify the only variables that we are going to expose to the expression.
let scope = {
  Math,
  deltaX: 10,
  deltaY: 10
};

// Expressions interact with a JsExpressionContext API for ultimate flexibility. This is the default implementation.
let expressionContext = createDefaultJsExpressionContext(scope);

// Evaluate the expression
let outcome = expression(expressionContext);

Only expressions are supported, so no assignments, code blocks, etc.

Features

• Uses native eval, so it is very fast
• Very tiny footprint (<2 Kb gzipped)
• Tested extensively for security
• Custom functionality can be provided using helper functions and objects

Some limitations:

• String literals must use double quotes (no single quotes or interpolation).
• Regular expressions cannot use the literal notation.
• Lambda functions cannot have parameters (see example-tests.ts on how to deal with this limitation).
• You cannot access functions on an object's prototype (like "".substr(1)). This is by design and you can use helper functions to access them.
• Object literals are not yet supported. Support can still be added easily if the keys require quotes (JSON style).