Esprima .NET (BSD license) is a .NET port of the esprima.org project. It is a standard-compliant ECMAScript parser (also popularly known as JavaScript).

Features

• Full support for ECMAScript 2019 (ECMA-262 10th Edition)
• Sensible syntax tree format as standardized by ESTree project
• Optional tracking of syntax node location (index-based and line-column)
• Heavily tested

API

Esprima can be used to perform lexical analysis (tokenization) or syntactic analysis (parsing) of a JavaScript program.

A simple C# example:

var parser = new JavaScriptParser("const answer = 42");
var program = parser.ParseProgram();

Will return this when serialized in json:

{
    "type": "Program",
    "body": [
        {
            "type": "VariableDeclaration",
            "declarations": [
                {
                    "type": "VariableDeclarator",
                    "id": {
                        "type": "Identifier",
                        "name": "answer"
                    },
                    "init": {
                        "type": "Literal",
                        "value": 42,
                        "raw": "42"
                    }
                }
            ],
            "kind": "const"
        }
    ],
    "sourceType": "script"
}

Benchmarks

Here is a list of common JavaScript libraries and the time it takes to parse them, compared to the time it took for the same script using the original Esprima in Chrome.

Script	Size	Esprima .NET	Esprima (Chrome)
underscore-1.5.2	43 KB	2.4 ms	3.1 ms
backbone-1.1.0	60 KB	2.9 ms	3.5 ms
mootools-1.4.5	163 KB	18.7 ms	16.2 ms
jquery-1.9.1	271 KB	22.8 ms	19.0 ms
yui-3.12.0	341 KB	17.2 ms	16.2 ms
jquery.mobile-1.4.2	456 K	43.3 ms	46.9 ms
angular-1.2.5	721 KB	29.3 ms	37.2 ms