Adds docs for JS client (#511)

docs/docs/clients/javascript.md

@@ -0,0 +1,99 @@
+# JS
+
+## Installation
+To install the SDK, use Yarn, npm, or a script tag:
+
+- npm
+```
+npm install @parcelvoy/js-sdk
+```
+
+- Yarn
+```
+yarn add @parcelvoy/js-sdk
+```
+
+script tag
+
+```
+<script src="https://unpkg.com/@parcelvoy/js-sdk/lib/esm/index.js"></script>
+```
+
+## Usage
+The SDK can be used both on the server or in the web browser. The main difference is that on the Browser the identified user will be cached vs in Node where you'll need to pass in identifiers on every request.
+
+### Initialize
+Before using any methods, the library must be initialized with an API key and URL endpoint.
+
+If you aren't accessing the SDK via script tag, start by importing the Parcelvoy SDK:
+```typescript
+
+// 
+const { Client /** or BrowserClient */ } = require('@parcelvoy/js-sdk')
+
+// Or
+import { Client /** or BrowserClient */ } from '@parcelvoy/js-sdk'
+```
+
+Then you can initialize the library:
+```typescript
+// Node
+const client = new Client({
+    apiKey: "XXX-XXX",
+    urlEndpoint: "https://app.parcelvoy.com/api"
+})
+
+// Browser
+const client = new BrowserClient({
+    apiKey: "XXX-XXX",
+    urlEndpoint: "https://app.parcelvoy.com/api"
+})
+
+// Or global script
+Parcelvoy.initialize({
+    apiKey: "XXX-XXX",
+    urlEndpoint: "https://app.parcelvoy.com/api"
+})
+```
+
+### Identify
+You can handle the user identity of your users by using the `identify` method. This method works in combination to either/or associate a given user to your internal user ID (`external_id`) or to associate attributes (traits) to the user. By default all events and traits are associated with an anonymous ID until a user is identified with an `external_id`. From that point moving forward, all updates to the user and events will be associated to your provider identifier.
+```typescript
+
+// Client
+client.identify({
+    externalId: "XXX-XXX"
+    phone: "+1234567890"
+    email: "email@email.com"
+    traits: {}
+})
+
+// Or global script
+Parcelvoy.identify({
+    externalId: "XXX-XXX"
+    phone: "+1234567890"
+    email: "email@email.com"
+    traits: {}
+})
+```
+
+### Events
+If you want to trigger a journey and list updates off of things a user does within your app, you can pass up those events by using the `track` method.
+```typescript
+
+// Client
+client.track({
+    event: "Tapped Button"
+    traits: {
+        "Key": "Value"
+    }
+})
+
+// Or global script
+Parcelvoy.track({
+    event: "Tapped Button",
+    traits: {
+        "Key": "Value"
+    }
+})
+```