fix(Stepper): format scientific number (#13709)

packages/vant/src/stepper/Stepper.tsx

@@ -91,6 +91,11 @@ export default defineComponent({
         return value;
       }
 
+      // format scientific number
+      if (typeof value === 'number' && String(value).includes('e')) {
+        value = value.toFixed(decimalLength ? +decimalLength : 17); // 17 is the max precision of a JS number
+      }
+
       value = formatNumber(String(value), !props.integer);
       value = value === '' ? 0 : +value;
       value = Number.isNaN(value) ? +min : value;

packages/vant/src/stepper/test/index.spec.ts

@@ -455,3 +455,30 @@ test('should allow input be to empty when using allow-empty prop', async () => {
   await input.trigger('blur');
   expect(wrapper.emitted('update:modelValue')![0]).toEqual([1]);
 });
+
+test('scientific number', async () => {
+  const wrapper = mount(Stepper, {
+    props: {
+      min: 0,
+      modelValue: 9.9e-7,
+    },
+  });
+
+  const input = wrapper.find('input');
+
+  expect(input.element.value).toEqual('9.9e-7');
+});
+
+test('scientific number with decimal length', async () => {
+  const wrapper = mount(Stepper, {
+    props: {
+      min: 0,
+      modelValue: 9.9e-7,
+      decimalLength: 8,
+    },
+  });
+
+  const input = wrapper.find('input');
+
+  expect(input.element.value).toEqual('0.00000099');
+});