Appendix A. Syntax Tree Format

Esprima syntax tree format is derived from the original version of Mozilla Parser API, which is then formalized and expanded as the ESTree specification.

Note: In the following sections, interfaces are described using the syntax of TypeScript interface.

Each node is represented as a regular JavaScript object that implements the interface:

interface Node {
  type: string;
}

The type property is a string that contains the variant type of the node. Each subtype of Node is explained in the subsequent sections.

When the node is annotated with its location, the interface becomes:

interface Node {
  type: string;
  range?: [number, number];
  loc?: SourceLocation;
}

with the source location defined as:

interface Position {
    line: number;
    column: number;
}
 
interface SourceLocation {
    start: Position;
    end: Position;
    source?: string | null;
}