Readme: more detailed examples for module code

README.md

@@ -8,7 +8,7 @@ eshost-cli makes it easy to run and compare ECMAScript code uniformly across a n
 
 See eshost's [supported hosts](https://github.com/bterlson/eshost#supported-hosts) for a list of hosts, download/build locations, and other information.
 
-### Usage
+## Usage
 
 See `--help` output for the full details. Basic usage:
 
@@ -22,29 +22,33 @@ See `--help` output for the full details. Basic usage:
   - `eshost -mx "foo = 42; print(foo);"` (this example should result in errors!)
 * Execute a source file as module code by saving the file with an `.mjs` extension: `eshost file.mjs`; or by using the `-m` option: `eshost -m file.js`
 
-#### Examples
+### Examples
 
 ```
 $ npm install -g eshost-cli
 $ eshost --help
 $ eshost --add <name> <type> <path to host executable> --args <optional arguments>
 $ eshost -e "Map.length"
+#### Chakra
+0
 
-## chakra-es6
+#### engine262
 0
 
-## d8
+#### JavaScriptCore
 0
 
-## chakra
+#### SpiderMonkey
 0
 
-## spidermonkey
-1
+#### V8
+0
 
-## node
+#### XS
 0
+```
 
+```
 $ eshost --configure-jsvu --jsvu-prefix jsvu
 $ eshost --tags jsvu-web -itsx "let a = 40+2; print(a)"
 
@@ -59,7 +63,65 @@ let a = 40+2; print(a)
 └──────────┴────┘
 ```
 
-### Managing Hosts
+### Rules For Module Code
+
+Files containing the imported modules must be located in the same directory that the "entry point" file is located. Please read and accept the following examples.
+
+1. Executing a program with module dependencies, where the entry point is a ".mjs" file: 
+
+  ```
+  mkdir entry-point-mjs;
+  cd entry-point-mjs;
+  echo "export var a = 1;" >> export.mjs
+  echo "import {a} from './export.mjs'; print(a);" >> import.mjs
+
+  eshost --host="engine262,JavaScriptCore,SpiderMonkey,V8,XS" import.mjs
+  #### engine262
+  1
+
+  #### JavaScriptCore
+  1
+
+  #### SpiderMonkey
+  1
+
+  #### V8
+  1
+
+  #### XS
+  1
+  ```
+
+2. Executing a program with module dependencies, where the entry point is a ".js" file: 
+
+  (Notice the use of the `-m` flag, **this is required for ".js" files**)
+  ```
+  mkdir entry-point-js;
+  cd entry-point-js;
+  echo "export var a = 1;" >> export.mjs
+  echo "import {a} from './export.mjs'; print(a);" >> import.js
+
+  eshost --host="engine262,JavaScriptCore,SpiderMonkey,V8,XS" -m import.js
+  #### engine262
+  1
+
+  #### JavaScriptCore
+  1
+
+  #### SpiderMonkey
+  1
+
+  #### V8
+  1
+
+  #### XS
+  1
+  ```
+
+**Executing a multi-line program with module dependencies is not yet supported. Support is in progress.**
+
+
+## Managing Hosts
 
 You can `--list`, `--add`, `--edit`, and `--delete` hosts. Adding a host requires a name, type, and path to the runtime executable. You can optionally pass arguments using `--args`. The same host can be added multiple times with different `--args` which makes it easy to compare the output of runtimes given different options (e.g. by turning language features on and off).