Incremental PR towards #347

src/number_format.js

@@ -149,7 +149,7 @@ class NumberFormat extends React.Component {
 
       const lastValueWithNewFormat = this.formatNumString(lastNumStr);
 
-      const formattedValue = props.value === undefined ? lastValueWithNewFormat : this.formatValueProp();
+      const formattedValue = props.value === undefined || props.value === null ? lastValueWithNewFormat : this.formatValueProp();
       const numAsString = this.removeFormatting(formattedValue);
 
       const floatValue = parseFloat(numAsString);

test/library/format_as_text.spec.js

@@ -42,7 +42,7 @@ describe('NumberFormat as text', () => {
     expect(wrapper.find('span').text()).toEqual('4111.36');
   });
 
-  it('it should add zeros if fixedDecimalScale is provided', () => {
+  it('should add zeros if fixedDecimalScale is provided', () => {
     const wrapper = shallow(<NumberFormat value="4111.11" displayType={'text'} decimalScale={4} fixedDecimalScale={true}/>);
     expect(wrapper.find('span').text()).toEqual('4111.1100');
 

test/library/input.spec.js

@@ -56,6 +56,33 @@ describe('NumberFormat as input', () => {
     expect(wrapper.find('input').instance().value).toEqual('$2,456,981');
   });
 
+  it('should load the default value when initial value is null', () => {
+    const wrapper = mount(<NumberFormat value={null} defaultValue={89} />);
+    expect(wrapper.state().value).toEqual('89');
+  });
+
+  it('should load the prevous valid value if the state is changed to null', () => {
+    class WrapperComponent extends React.Component {
+      constructor() {
+        super ();
+        this.state = {
+          testState: 90,
+        };
+      }
+      render() {
+        return (<NumberFormat value={this.state.testState} />)
+      }
+    }
+
+    const wrapper = mount(<WrapperComponent />);
+    const input = wrapper.find('input');
+    const domInput = input.instance();
+
+    expect(domInput.value).toEqual('90');
+    wrapper.setState({testState: null});
+    expect(domInput.value).toEqual('90');
+  });
+
   it('should use defaultValue as initial value', () => {
     const wrapper = mount(<NumberFormat defaultValue={2456981} thousandSeparator={true} prefix={'$'} />);
     expect(wrapper.state().value).toEqual('$2,456,981');