fix empty dropdown regression

CHANGELOG.md

@@ -107,4 +107,8 @@
     Issue: https://github.com/plotly/dash-table/issues/77
 
     First click selects the cell's content and will cause user input to override the cell content.
-    Second click into the cell will remove the selection and position the cursor accordingly.
+    Second click into the cell will remove the selection and position the cursor accordingly.
+
+## RC14 - Empty dropdown setting value regression fix
+
+    Issue: https://github.com/plotly/dash-table/issues/83

dash_table/package.json

@@ -1,6 +1,6 @@
 {
   "name": "dash-table",
-  "version": "3.0.0rc13",
+  "version": "3.0.0rc14",
   "description": "Dash table",
   "main": "build/index.js",
   "scripts": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "dash-table",
-  "version": "3.0.0rc13",
+  "version": "3.0.0rc14",
   "description": "Dash table",
   "main": "build/index.js",
   "scripts": {

src/core/comparer.ts

@@ -1,5 +1,8 @@
 function isPlainObject(candidate: any) {
-    return typeof candidate === 'object' && candidate.constructor === Object;
+    return candidate !== undefined &&
+        candidate !== null &&
+        typeof candidate === 'object' &&
+        candidate.constructor === Object;
 }
 
 export function isEqual(obj1: object, obj2: object, deep: boolean = false) {

tests/e2e/cypress/integration/edit_cell_test.ts

@@ -7,6 +7,31 @@ describe('edit cell', () => {
         cy.visit('http://localhost:8080');
     });
 
+    it('can delete dropdown', () => {
+        DashTable.getCell(0, 8).trigger('mouseover');
+        DashTable.getCell(0, 8).within(() => cy.get('.Select-clear').click());
+        DashTable.getCell(0, 8).within(() => cy.get('.Select-placeholder').should('exist'));
+    });
+
+    it('can delete dropdown and set value', () => {
+        DashTable.getCell(0, 8).trigger('mouseover');
+        DashTable.getCell(0, 8).within(() => cy.get('.Select-clear').click());
+        DashTable.getCell(0, 8).within(() => cy.get('.Select-placeholder').should('exist'));
+
+        DashTable.getCell(0, 8).within(() => cy.get('div.Select').click()).then(() => {
+            DashTable.getCell(0, 8).within(() => {
+                cy.get('.Select-option').then($options => {
+                    const target = $options[0];
+                    if (target) {
+                        cy.wrap(target).click({ force: true });
+                    }
+                });
+            });
+        });
+
+        DashTable.getCell(0, 8).within(() => cy.get('.Select-placeholder').should('not.exist'));
+    });
+
     it('can edit dropdown', () => {
         let initialValue: string;
         let expectedValue: string;