Feat/hx reselect support unset (#3153)

feat: handle 'unset'for HX-Reselect in swap function (+ test)

Author: oliverhaas

src/htmx.js

@@ -4822,7 +4822,7 @@ var htmx = (function() {
           }
 
           swap(target, serverResponse, swapSpec, {
-            select: selectOverride || select,
+            select: selectOverride === 'unset' ? null : selectOverride || select,
             selectOOB,
             eventInfo: responseInfo,
             anchor: responseInfo.pathInfo.anchor,

test/core/headers.js

@@ -299,6 +299,16 @@ describe('Core htmx AJAX headers', function() {
     div.innerHTML.should.equal('<div id="d2">bar</div>')
   })
 
+  it('should handle HX-Reselect unset', function() {
+    this.server.respondWith('GET', '/test', [200, { 'HX-Reselect': 'unset' }, 'bar'])
+
+    var div = make('<div hx-get="/test" hx-select="#d2"></div>')
+    div.click()
+    this.server.respond()
+
+    div.innerHTML.should.equal('bar')
+  })
+
   it('should handle simple string HX-Trigger-After-Swap response header properly w/ outerHTML swap', function() {
     this.server.respondWith('GET', '/test', [200, { 'HX-Trigger-After-Swap': 'foo' }, ''])