Merge pull request #22 from alsiola/master

This will be released on `0.1.5`

README.md

@@ -51,6 +51,22 @@ notify.show('Toasty!');
 
 ```
 
+## Queued Notifications
+
+A notification queue can be created using the createShowQueue function, for example, in the constructor of a component:
+
+````js
+constructor() {
+    super();
+    this.show = notify.createShowQueue();
+}
+````
+This queue can then be used with the same API as the notify.show function:
+
+````js
+this.show('Toasty!');
+````
+
 ## Options
 
 The toast notification function `notify.show()` supports `message`, `type` and `timeout` attributes in the following way.
@@ -81,3 +97,9 @@ You can also pass `-1` to cause the notification to display persistently.
 let myColor = { background: '#0E1717', text: "#FFFFFF" };
 notify.show("this is sample text", "custom", 5000, myColor);
 ```
+
+The createShowQueue function has two optional arguments:
+
+* `initialRecallDelay` is how long (in ms) to wait if the first attempt at showing a notification fails (because a non-queued notification was already being shown). Default: 500ms
+
+* `recallDelayIncrement` is a time (in ms) added to the recallDelay after each failed attempt.  This is to mitigate numerous rapidly-repeated calls in the case of a non-queued notification being shown without a timeout. Default 500ms

src/notify.js

@@ -187,6 +187,7 @@ function hideToast() {
 /* Public functions */
 
 /* Show Animated Toast Message */
+/* Returns true if the toast was shown, or false if show failed due to an existing notification */
 function show(text, type, timeout, color) {
 	if (!document.getElementById(notificationWrapperId).hasChildNodes()) {
 		let renderTimeout = timeout;
@@ -207,9 +208,60 @@ function show(text, type, timeout, color) {
 		setTimeout(function() {
 			hideToast();
 		}, renderTimeout + animationDuration);
+
+        return true;
 	}
+    return false;
 }
 
+/* Add to Animated Toast Message Queue */
+/* Display immediately if no queue     */
+/* initialRecallDelay: If the call to show fails because of an existing notification, how long to wait until we retry (ms) */
+/* recallDelayIncrement: Each time a successive call fails, the recall delay will be incremented by this (ms) */
+function createShowQueue(initialRecallDelay = 500, recallDelayIncrement = 500) {
+
+    // Array to hold queued messages
+    this.msgs = [];
+
+    // Is the showNotify function in progress - used so we can call showNotify when a
+    // message is added to an empty queue.
+    this.isNotifying = false;
+
+    this.currentRecallDelay = initialRecallDelay;
+
+    // Retrieve the next message from the queue and try to show it
+    this.showNotify = () => {
+        // If there are no messages in the queue
+        if (this.msgs.length ===0) {
+            this.isNotifying = false;
+            return;
+        }
+
+        this.isNotifying = true;
+
+        const current = this.msgs.pop();
+
+        // show will now return true if it is able to send the message, or false if there is an existing message
+        if (show(current.text, current.type, current.timeout, current.color)) {
+            this.currentRecallDelay = initialRecallDelay;
+            if (current.timeout > 0) {
+                setTimeout(() => this.showNotify(), current.timeout + animationDuration);
+            }
+        } else {
+            // If message show failed, re-add the current message to the front of the queue
+            this.msgs.unshift(current);
+            setTimeout(() => this.showNotify(), this.currentRecallDelay);
+            this.currentRecallDelay += recallDelayIncrement;
+        }
+    }
+
+    return (text, type = '', timeout = defaultTimeout, color = colorWhite) => {
+        this.msgs.push({ text, type, timeout, color });
+        if (!this.isNotifying) {
+            this.showNotify();
+        }
+    }
+}
 
 /* Export notification container */
 export default class extends React.Component {
@@ -222,5 +274,6 @@ export default class extends React.Component {
 
 /* Export notification functions */
 export let notify = {
-	show
+	show,
+    createShowQueue
 };