create js file for placeholder image functionality

Author: dzoladz

assets/js/placeholder.js

@@ -0,0 +1,33 @@
+/**********************************************************************
+Generates a random placeholder image for a speaker
+
+css:    css class for <img> element
+name:   identifier for the speaker that gets hashed
+path:   the path to the image with a # for the image. # gets replaced
+alt:    alt text for the image
+num:    total number of placeholder image options for modulo
+***********************************************************************/
+
+function placeholderImage(css, name, path, alt, num) {
+    const hashCode = function(str) {
+        if (Array.prototype.reduce) {
+            return str.split("").reduce(function(a,b){a=((a<<5)-a)+b.charCodeAt(0);return a&a},0);
+        } else {
+            var hash = 0, i, chr, len;
+            if (str.length == 0) return hash;
+            for (i = 0, len = str.length; i < len; i++) {
+                chr = str.charCodeAt(i);
+                hash = ((hash << 5) - hash) + chr;
+                hash |= 0; // Convert to 32bit integer
+            }
+            return hash;
+        }
+    };
+
+    var output = '<img ';
+    output += 'class="' + css + '" ';
+    output += 'alt="' + alt + '" ';
+    output += 'src="' + path.replace('#', Math.abs(hashCode(name)) % 10) + '" ';
+    output = output.trim() + '>';
+    document.write(output);
+}