What parse returns

parse returns an object. It always has two keys: the node, and where the parse stopped.

const { node, end } = source.parse();

node is the tree. Every node in it has start and end, offsets into the text you gave the Source. The end beside node is the offset where the parse stopped reading. For a whole program that is the end of the text.

These pages call that object the answer.

Options

Each option adds one key to the answer, or one property to the nodes. A key is present only when its option is on.

• locations puts loc, with line and column, on every node.
• comments adds comments, every comment in source order, and puts leadingComments, trailingComments and innerComments on the nodes.
• scopes adds scopes, bindings and references, and lets you ask any node what it declares or refers to. See Scopes.
• errorRecovery adds errors and returns a tree instead of throwing. See Errors.
• typescript reads TypeScript. typescript: 'erase' also removes it, and adds typescript, the list of what could not be removed. See TypeScript.
• parenthesized puts parenthesized: true on every node that was written in parentheses.
• sourceType: 'module' reads strict code, with import, export and top-level await.
• scopes, on a file read with a grammar, also adds roots, one entry per piece of JavaScript in it. See Parsing with a grammar.

Every option, with its type and default, is in the reference.

Positions

Offsets are UTF-16, the way JavaScript strings count. They are offsets into the whole text, however small a piece you parsed, so nothing has to be added to them. The answer's end is past any closing parentheses around the node and any comment after it.