Getting Started

This package is available in the Node Package Repository and can be easily installed with npm or yarn.

$ npm i @nodesecure/estree-ast-utils
# or
$ yarn add @nodesecure/estree-ast-utils

API

Most utility options extend the DefaultOptions interface:

export interface DefaultOptions {
  externalIdentifierLookup?(name: string): string | null;
}

You can provide a custom externalIdentifierLookup function to enable the utilities to resolve identifiers from external sources—such as VariableTracer, for example.

Transforms an ESTree ArrayExpression into an iterable of literal values.

["foo", "bar"];

will yield "foo", then "bar".

export interface ArrayExpressionToStringOptions extends DefaultOptions {
  /**
   * When enabled, resolves the char code of the literal value.
   *
   * @default true
   * @example
   * [65, 66] // => ['A', 'B']
   */
  resolveCharCode?: boolean;
}

Compute simple ArrayExpression that are using a CallExpression join()

{
  host: [
    ["goo", "g", "gle"].join(""),
    "com"
  ].join(".")
}

Will return google.com

Returns all Literal nodes from a binary expression.

"foo" + "bar";

Will yield "foo", then "bar".

Options are described by the following interface:

interface ConcatBinaryExpressionOptions extends DefaultOptions {
  /**
   * When set to true, the function will throw an error if it encounters
   * a node type that is not supported (i.e., not a Literal, BinaryExpr, ArrayExpr or Identifier).
   *
   * @default false
   * @example
   * "foo" + fn() + "bar" // <- will throw an error if `stopOnUnsupportedNode` is true
   */
  stopOnUnsupportedNode?: boolean;
}

Recursively extracts all LogicalExpression components.

{ operator: "||" | "&&" | "??", node: ESTree.Expression }

For example:

freeGlobal || freeSelf || Function('return this')();

Will yield three components:

• freeGlobal
• freeSelf
• and finally Function('return this')();

Returns the literal arguments of a CallExpression.

For example:

eval("require");

Returns

["require"]

Returns the identifier name of a CallExpression, or null if not resolvable.

foobar();

Returns "foobar".

By default, it resolves member expressions. This can be disabled with resolveCallExpression: false.

require('./file.js')();
//     ^ Second     ^ First

With resolveCallExpression: false, the function will return null.

interface GetCallExpressionIdentifierOptions extends DefaultOptions {
  /**
   * Resolve the CallExpression callee if it is a MemberExpression.
   *
   * @default true
   * @example
   * require('./file.js')();
            ^ Second     ^ First
   */
  resolveCallExpression?: boolean;
}

Returns the identifier chain from a MemberExpression.

foo.bar();

will return "foo" then "bar".

Extracts all variable identifiers from a declaration.

const [foo, bar] = [1, 2];

will return "foo" then "bar".

License

MIT