angular-expressions

angular's nicest part extracted as a standalone module for the browser and node.

angular-expressions exposes a .compile()-method which can be used to compile evaluable expressions:

var expressions = require("angular-expressions");

evaluate = expressions.compile("1 + 1");
evaluate(); // returns 2

You can also set and get values on a given scope:

evaluate = expressions.compile("name");
scope = { name: "Jenny" };
evaluate(scope); // returns 'Jenny'

evaluate = expressions.compile("ship.pirate.name = 'Störtebeker'");
evaluate(scope); // won't throw an error because angular's expressions are forgiving
console.log(scope.ship.pirate.name); // prints 'Störtebeker'

For assigning values, you can also use .assign():

evaluate = expressions.compile("ship.pirate.name");
evaluate.assign(scope, "Störtebeker");
console.log(scope.ship.pirate.name); // prints 'Störtebeker'

Check out their readme for further information.

Setup

Filters

Angular provides a mechanism to define filters on expressions:

expressions.filters.uppercase = (input) => input.toUpperCase();

expr = expressions.compile("'arr' | uppercase");
expr(); // returns 'ARR'

Arguments are evaluated against the scope:

expressions.filters.currency = (input, currency, digits) => {
  input = input.toFixed(digits);

  if (currency === "EUR") {
    return input + "€";
  } else {
    return input + "$";
  }
};

expr = expressions.compile("1.2345 | currency:selectedCurrency:2");
expr({
  selectedCurrency: "EUR",
}); // returns '1.23€'

If you need an isolated filters object, this can be achieved by setting the filters attribute in the options argument. Global cache is disabled if using options.filters. To setup an isolated cache, you can also set the cache attribute in the options argument:

var isolatedFilters = {
  transform: (input) => input.toLowerCase(),
};
var isolatedCache = {};

var resultOne = expressions.compile("'Foo Bar' | transform", {
  filters: isolatedFilters,
  cache: isolatedCache,
});

console.log(resultOne()); // prints 'foo bar'
console.log(isolatedCache); // prints '{"'Foo Bar' | transform": [Function fn] }'

API

exports

.compile(src): Function

Compiles src and returns a function evaluate(). The compiled function is cached under compile.cache[src] to speed up further calls.

Compiles also export the AST.

Example output of: compile("tmp + 1").ast

{ type: 'Program',
  body:
   [ { type: 'ExpressionStatement',
       expression:
        { type: 'Identifier',
          name: 'tmp',
          constant: false,
          toWatch: [ [Circular] ] } } ],
  constant: false }

NOTE angular $parse do not export ast variable it's done by this library.

.compile.cache = Object.create(null)

A cache containing all compiled functions. The src is used as key. Set this on false to disable the cache.

.filters = {}

An empty object where you may define your custom filters.

.Lexer

The internal Lexer.

.Parser

The internal Parser.

evaluate(scope?): *

Evaluates the compiled src and returns the result of the expression. Property look-ups or assignments are executed on a given scope.

evaluate.assign(scope, value): *

Tries to assign the given value to the result of the compiled expression on the given scope and returns the result of the assignment.

In the browser

There is no dist build because it's not 2005 anymore. Use a module bundler like webpack or browserify. They're both capable of CommonJS and AMD.

Security

Security recommendation

If you are running in Node.JS, we recommend you to use the following flag in your node command so that access to __proto__ is not possible.

This puts an additional security layer which makes vulnerabilities much less likely to affect you.

The flag can be set like this :

node --disable-proto=delete app.js

If you're using some libraries that still rely on Prototype, this could break your application.

User Precaution

When providing data or filters to the library, ensure that you do not include "eval", "Function", or any filters that internally invoke these functions, as doing so could expose your users to the risk of Remote Code Execution (RCE).

Authorship

Kudos go entirely to the great angular.js team, it's their implementation!

Contributing

Suggestions and bug-fixes are always appreciated. Don't hesitate to create an issue or pull-request. All contributed code should pass

1. the tests in node.js by running npm test
2. the tests in all major browsers by running npm run test-browser and then visiting http://localhost:8080/bundle

License

Unlicense

Sponsors