diff --git a/src/compiler/intermediate.js b/src/compiler/intermediate.js
index 6f66673b..55518929 100644
--- a/src/compiler/intermediate.js
+++ b/src/compiler/intermediate.js
@@ -1,31 +1,84 @@
+/**
+ * @fileoverview Common intermediates shared amongst parts of the compiler.
+ */
+
+/**
+ * An IntermediateScript describes a single script.
+ * A script is anything with a hat -- "when green flag starts", a procedure definition, etc.
+ */
 class IntermediateScript {
     constructor () {
+        /**
+         * List of nodes that make up this script.
+         * @type {Array|null}
+         */
         this.stack = null;
 
+        /**
+         * Whether this script is a procedure.
+         * @type {boolean}
+         */
         this.isProcedure = false;
+
+        /**
+         * The name of this procedure, if any.
+         * @type {string}
+         */
         this.procedureCode = '';
+
+        /**
+         * List of arguments accepted by this function, if it is a procedure.
+         * @type {string[]}
+         */
         this.arguments = [];
 
+        /**
+         * Whether this script should be run in warp mode.
+         * @type {boolean}
+         */
         this.isWarp = false;
 
+        /**
+         * Whether this script can `yield`
+         * If false, this script will be compiled as a regular JavaScript function (function)
+         * If true, this script will be compiled as a generator function (function*)
+         * @type {boolean}
+         */
         this.yields = false;
 
+        /**
+         * Whether this script should use the "warp timer"
+         * @type {boolean}
+         */
         this.warpTimer = false;
 
+        /**
+         * List of procedure IDs that this script needs.
+         * @readonly
+         */
         this.dependedProcedures = [];
 
+        /**
+         * Cached result of compiling this script.
+         * @type {Function|null}
+         */
         this.cachedCompileResult = null;
     }
 }
 
+/**
+ * An IntermediateRepresentation contains scripts.
+ */
 class IntermediateRepresentation {
     constructor () {
         /**
+         * The entry point of this IR.
          * @type {IntermediateScript}
          */
         this.entry = null;
 
         /**
+         * Maps procedure IDs to their intermediate script.
          * @type {Object.<string, IntermediateScript>}
          */
         this.procedures = {};
diff --git a/src/compiler/jsgen.js b/src/compiler/jsgen.js
index 7258971d..b18b27a4 100644
--- a/src/compiler/jsgen.js
+++ b/src/compiler/jsgen.js
@@ -3,6 +3,7 @@ const Cast = require('../util/cast');
 const VariablePool = require('./variable-pool');
 const execute = require('./execute');
 const {disableToString} = require('./util');
+const {IntermediateScript, IntermediateRepresentation} = require('./intermediate');
 const environment = require('./environment');
 
 /**
@@ -292,6 +293,11 @@ const isSafeConstantForEqualsOptimization = input => {
 };
 
 class JSGenerator {
+    /**
+     * @param {IntermediateScript} script 
+     * @param {IntermediateRepresentation} ir 
+     * @param {Target} target 
+     */
     constructor (script, ir, target) {
         this.script = script;
         this.ir = ir;