uiur / mjs

minimal javascript interpreter in c

mjs

A minimal (toy) JavaScript interpreter.

The goal is that it can be used as a good subset of ES5.

The implementation is from scratch. It doesn't have any library dependencies except for standard C library. The parser and lexer are written as a recursive descendant parser.

motivation

What I cannot create, I do not understand - Richard Feynman

The motivation is to:

• learn C language
• learn algorithms and data structures such as hash table
• learn how to build an interpreter of a dynamic-typed language
• know more deeply about JavaScript

status

• It can run sort algorithms
• It has very basic object system with prototype chains

development

Here's a note for myself.

build

make
./build/main test/input/8-array-sort.js

test

This runs unit tests in C and end-to-end tests in shell scripts.

make test_run

examples

see test/input

function sort(items) {
  for (var i = 0; i < items.length; i = i + 1) {
    var j = 0;
    var stop = items.length - 1;
    for (; j < stop; j = j + 1){
      if (items[j] > items[j + 1]){
        var temp = items[j];
        items[j] = items[j + 1];
        items[j + 1] = temp;
      }
    }
  }

  return items;
}

Array.prototype.sort = function () {
  return sort(this);
};

console.log([3, 2, 1].sort());