Which ECMAScript Versions and Syntax Does Esprima Support?

Esprima fully supports ECMAScript 2019 (ECMA-262 10th Edition). If your project targets ES2019 or earlier, Esprima can tokenize and parse it. It also offers experimental support for JSX, the syntax extension used by React. Anything newer than ES2019 — for example, syntax introduced in later ECMAScript editions — is not covered by the documented support, so verify before relying on it.

Supported language scope

What "full support for ECMAScript 2019" means in practice

Esprima performs lexical analysis (tokenization) or syntactic analysis (parsing) of a JavaScript program. The documented example on Node.js:

> var esprima = require('esprima');
> var program = 'const answer = 42';
> esprima.tokenize(program);
[ { type: 'Keyword', value: 'const' },
  { type: 'Identifier', value: 'answer' },
  { type: 'Punctuator', value: '=' },
  { type: 'Numeric', value: '42' } ]
> esprima.parse(program);
{ type: 'Program',
  body: [ { type: 'VariableDeclaration', declarations: [Object], kind: 'const' } ],
  sourceType: 'script' }

tokenize returns a flat list of tokens; parse returns a full syntax tree. Once you have the tree, you can apply static analysis such as syntax visualization, code validation, and editing autocomplete with type inferencing. Regenerating code from the tree enables transformations from simple rewriting with specific formatting to more complicated minification.

Choosing Esprima for your project

• Pick Esprima if you need a standard-compliant parser for ES2019-or-earlier JavaScript, want a syntax tree with optional node location info, or need to experiment with JSX parsing.
• Be cautious if your source uses syntax from ECMAScript editions after 2019, or if you need production-grade JSX handling — the JSX support is documented as experimental.
• Consider the maintenance signal: Esprima is created and maintained by Ariya Hidayat, with a Git repository, continuous integration, unit tests, benchmarks, and a speed comparison suite listed among its project resources.

Verifying support yourself

1. Install or require Esprima in your environment.
2. Run esprima.parse() on a representative file from your codebase.
3. Check whether parsing succeeds and whether the resulting tree matches the constructs you expect.
4. For JSX, test a component file separately, since that support is experimental.

If parsing fails on syntax your project uses, that construct is outside the documented support and you should look for a parser with a newer language baseline.