From 47a3dc8ba54b59deb825fd0762400db078b1a8af Mon Sep 17 00:00:00 2001
From: Jeremy Likness <jeremy@jeremylikness.com>
Date: Tue, 26 Nov 2019 09:15:12 -0800
Subject: [PATCH] Refactor data-binding to own class

---
 js/dataBinding.js | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 js/slide.js       | 42 ++++++++++-----------------------------
 2 files changed, 60 insertions(+), 32 deletions(-)
 create mode 100644 js/dataBinding.js

diff --git a/js/dataBinding.js b/js/dataBinding.js
new file mode 100644
index 0000000..7f64211
--- /dev/null
+++ b/js/dataBinding.js
@@ -0,0 +1,50 @@
+// @ts-check
+
+export class DataBinding {
+    
+    /**
+     * Simple evaluation
+     * @param {string} js The JavaScript to evaluate 
+     */
+    execute(js) {
+        return eval(js);
+    }
+
+    /**
+     * Evaluates JavaScript with a constrained context (scope)
+     * @param {string} src The JavaScript to evaluate 
+     * @param {object} context The context (data) to evaluate with
+     * @returns {object} The result of the evaluation 
+     */
+    executeInContext(src, context) {
+        return this.execute.call(context, src);
+    }
+
+    /**
+     * Searches for "repeat" attribute to data-bind lists
+     * @param {HTMLElement} elem The parent element to search 
+     * @param {object} context The context to use for binding 
+     */
+    bindLists(elem, context) {
+        const listBinding = elem.querySelectorAll("[repeat]");
+        listBinding.forEach(elem => {
+            const parent = elem.parentElement;
+            const expression = elem.getAttribute("repeat");
+            elem.removeAttribute("repeat");
+            const template = elem.outerHTML;
+            parent.removeChild(elem);
+            context[expression].forEach(item => {
+                let newTemplate = `${template}`;
+                const matches = newTemplate.match(/\{\{([^\}]*?)\}\}/g);
+                if (matches) {
+                    matches.forEach(match => {
+                        match = match.replace("{{", "").replace("}}", "");
+                        const value = this.executeInContext(`this.${match}`, {item});
+                        newTemplate = newTemplate.replace(`{{${match}}}`, value);                    
+                    });
+                    parent.innerHTML += newTemplate;
+                }               
+            });
+        });
+    }
+}
\ No newline at end of file
diff --git a/js/slide.js b/js/slide.js
index 7f9f770..e04a37b 100644
--- a/js/slide.js
+++ b/js/slide.js
@@ -1,4 +1,7 @@
 // @ts-check
+
+import {DataBinding} from "./dataBinding.js"
+
 /** 
  * Represents a slide 
  * */
@@ -19,6 +22,11 @@ export class Slide {
          * @type {object}
          */
         this._context = {};
+        /**
+         * Data binding helper
+         * @type {DataBinding}
+         */
+        this._dataBinding = new DataBinding();
         /** 
          * The HTML DOM hosting the slide contents
          * @type {HTMLDivElement}
@@ -57,41 +65,11 @@ export class Slide {
         // execute any scripts
         const script = this._html.querySelector("script");
         if (script) {
-            (function (/** @type {string} */src) {
-                return eval(src)
-            }).call(this._context, script.innerText);
-            this.dataBind();
+            this._dataBinding.executeInContext(script.innerText, this._context);
+            this._dataBinding.bindLists(this._html, this._context);
         }
     }
 
-    /**
-     * Scans for data-binding and applies the bindings
-     */
-    dataBind() {
-        const listBinding = this._html.querySelectorAll("[repeat]");
-        listBinding.forEach(elem => {
-            const parent = elem.parentElement;
-            const expression = elem.getAttribute("repeat");
-            elem.removeAttribute("repeat");
-            const template = elem.outerHTML;
-            parent.removeChild(elem);
-            this._context[expression].forEach(item => {
-                let newTemplate = `${template}`;
-                const matches = newTemplate.match(/\{\{([^\}]*?)\}\}/g);
-                if (matches) {
-                    matches.forEach(match => {
-                        match = match.replace("{{", "").replace("}}", "");
-                        const value = (function (/** @type {string} */src) {
-                            return eval(src)
-                        }).call({ item }, match);
-                        newTemplate = newTemplate.replace(`{{${match}}}`, value);                    
-                    });
-                    parent.innerHTML += newTemplate;
-                }               
-            });
-        });
-    }
-
     /** 
      * The slide transition
      * @returns {string} The transition name