detect multiple attribute and handle getting values

src/htmx.js

@@ -1235,6 +1235,9 @@ return (function () {
             if (shouldInclude(elt)) {
                 var name = getRawAttribute(elt,"name");
                 var value = elt.value;
+                if (!!getRawAttribute(elt, 'multiple')) {
+                    value = toArray(elt.querySelectorAll("option:checked")).map(function (e) { return e.value });
+                }
                 if (name != null && value != null) {
                     var current = values[name];
                     if(current) {

test/core/ajax.js

@@ -334,6 +334,38 @@ describe("Core htmx AJAX Tests", function(){
         }, 20);
     });
 
+    it('properly handles multiple select input', function()
+    {
+        var values;
+        this.server.respondWith("Post", "/test", function (xhr) {
+            values = getParameters(xhr);
+            xhr.respond(204, {}, "");
+        });
+
+        var form = make('<form hx-post="/test" hx-trigger="click">' +
+            '<select id="multiSelect" name="multiSelect" multiple="multiple">'+
+            '<option id="m1" value="m1">m1</option>'+
+            '<option id="m2" value="m2">m2</option>'+
+            '<option id="m3" value="m3">m3</option>'+
+            '<option id="m4" value="m4">m4</option>'+
+            '</form>');
+
+        form.click();
+        this.server.respond();
+        values.should.deep.equal({});
+
+        byId("m1").selected = true;
+        form.click();
+        this.server.respond();
+        values.should.deep.equal({multiSelect:"m1"});
+
+        byId("m1").selected = true;
+        byId("m3").selected = true;
+        form.click();
+        this.server.respond();
+        values.should.deep.equal({multiSelect:["m1", "m3"]});
+    });
+
     it('properly handles checkbox inputs', function()
     {
         var values;