diff --git a/src/.vuepress/components/forms-1.vue b/src/.vuepress/components/forms-1.vue new file mode 100644 index 0000000000..0df191b1f7 --- /dev/null +++ b/src/.vuepress/components/forms-1.vue @@ -0,0 +1,16 @@ + + + diff --git a/src/.vuepress/components/forms-2.vue b/src/.vuepress/components/forms-2.vue new file mode 100644 index 0000000000..46b694f95b --- /dev/null +++ b/src/.vuepress/components/forms-2.vue @@ -0,0 +1,18 @@ + + + diff --git a/src/.vuepress/components/forms-3.vue b/src/.vuepress/components/forms-3.vue new file mode 100644 index 0000000000..68c69a0654 --- /dev/null +++ b/src/.vuepress/components/forms-3.vue @@ -0,0 +1,16 @@ + + + diff --git a/src/.vuepress/components/forms-4.vue b/src/.vuepress/components/forms-4.vue new file mode 100644 index 0000000000..2d0063f0e5 --- /dev/null +++ b/src/.vuepress/components/forms-4.vue @@ -0,0 +1,22 @@ + + + diff --git a/src/.vuepress/components/forms-5.vue b/src/.vuepress/components/forms-5.vue new file mode 100644 index 0000000000..4244d0c97c --- /dev/null +++ b/src/.vuepress/components/forms-5.vue @@ -0,0 +1,21 @@ + + + diff --git a/src/.vuepress/components/forms-6.vue b/src/.vuepress/components/forms-6.vue new file mode 100644 index 0000000000..4bebf6074f --- /dev/null +++ b/src/.vuepress/components/forms-6.vue @@ -0,0 +1,21 @@ + + + diff --git a/src/.vuepress/components/forms-7.vue b/src/.vuepress/components/forms-7.vue new file mode 100644 index 0000000000..574fce39e7 --- /dev/null +++ b/src/.vuepress/components/forms-7.vue @@ -0,0 +1,21 @@ + + + diff --git a/src/.vuepress/components/forms-8.vue b/src/.vuepress/components/forms-8.vue new file mode 100644 index 0000000000..a3da617f2d --- /dev/null +++ b/src/.vuepress/components/forms-8.vue @@ -0,0 +1,25 @@ + + + diff --git a/src/.vuepress/config.js b/src/.vuepress/config.js index a573349d1f..293ea9745e 100644 --- a/src/.vuepress/config.js +++ b/src/.vuepress/config.js @@ -39,6 +39,7 @@ module.exports = { 'conditional', 'list', 'events', + 'forms' ] } ] diff --git a/src/guide/forms.md b/src/guide/forms.md new file mode 100644 index 0000000000..3571386c36 --- /dev/null +++ b/src/guide/forms.md @@ -0,0 +1,280 @@ +# Form Input Bindings + +## Basic Usage + +You can use the `v-model` directive to create two-way data bindings on form input, textarea, and select elements. It automatically picks the correct way to update the element based on the input type. Although a bit magical, `v-model` is essentially syntax sugar for updating data on user input events, plus special care for some edge cases. + +::: tip Note +`v-model` will ignore the initial `value`, `checked` or `selected` attributes found on any form elements. It will always treat the Vue instance data as the source of truth. You should declare the initial value on the JavaScript side, inside the `data` option of your component. +::: + +`v-model` internally uses different properties and emits different events for different input elements: + +- text and textarea elements use `value` property and `input` event; +- checkboxes and radiobuttons use `checked` property and `change` event; +- select fields use `value` as a prop and `change` as an event. + + +::: tip Note +For languages that require an [IME](https://en.wikipedia.org/wiki/Input_method) (Chinese, Japanese, Korean etc.), you'll notice that `v-model` doesn't get updated during IME composition. If you want to cater for these updates as well, use `input` event instead. +::: + +### Text + +```html + +

Message is: {{ message }}

+``` + + + +### Multiline text + +```html +Multiline message is: +

{{ message }}

+
+ +``` + + + +Interpolation on textareas won't work. Use `v-model` instead. + +```html + + + + + +``` + +### Checkbox + +Single checkbox, boolean value: + +```html + + +``` + + + +Multiple checkboxes, bound to the same Array: + +```html +
+ + + + + + +
+ Checked names: {{ checkedNames }} +
+``` + +```js +new Vue({ + el: '#example-3', + data: { + checkedNames: [] + } +}) +``` + + + +### Radio + +```html + + +
+ + +
+Picked: {{ picked }} +``` + + + +### Select + +Single select: + +```html +
+ + Selected: {{ selected }} +
+``` + +```js +Vue.createApp().mount( + { + data() { + return { + selected: '' + } + } + }, + '#example-select' +) +``` + + + +:::tip Note +If the initial value of your `v-model` expression does not match any of the options, the ` + + + + +
+Selected: {{ selected }} +``` + + + +Dynamic options rendered with `v-for`: + +```html +
+ + Selected: {{ selected }} +
+``` + +```js +Vue.createApp().mount( + { + data() { + return { + selected: 'A', + options: [ + { text: 'One', value: 'A' }, + { text: 'Two', value: 'B' }, + { text: 'Three', value: 'C' } + ] + } + } + }, + '#example-select-dynamic' +) +``` + + + +## Value Bindings + +For radio, checkbox and select options, the `v-model` binding values are usually static strings (or booleans for checkbox): + +```html + + + + + + + + +``` + +But sometimes we may want to bind the value to a dynamic property on the Vue instance. We can use `v-bind` to achieve that. In addition, using `v-bind` allows us to bind the input value to non-string values. + +### Checkbox + +```html + +``` + +```js +// when checked: +vm.toggle === 'yes' +// when unchecked: +vm.toggle === 'no' +``` + +:::tip Tip +The `true-value` and `false-value` attributes don't affect the input's `value` attribute, because browsers don't include unchecked boxes in form submissions. To guarantee that one of two values is submitted in a form (e.g. "yes" or "no"), use radio inputs instead. +::: + +### Radio + +```html + +``` + +```js +// when checked: +vm.pick === vm.a +``` + +### Select Options + +```html + +``` + +```js +// when selected: +typeof vm.selected // => 'object' +vm.selected.number // => 123 +``` + +## Modifiers + +### `.lazy` + +By default, `v-model` syncs the input with the data after each `input` event (with the exception of IME composition as [stated above](#vmodel-ime-tip)). You can add the `lazy` modifier to instead sync after `change` events: + +```html + + +``` + +### `.number` + +If you want user input to be automatically typecast as a number, you can add the `number` modifier to your `v-model` managed inputs: + +```html + +``` + +This is often useful, because even with `type="number"`, the value of HTML input elements always returns a string. If the value cannot be parsed with `parseFloat()`, then the original value is returned. + +### `.trim` + +If you want whitespace from user input to be trimmed automatically, you can add the `trim` modifier to your `v-model`-managed inputs: + +```html + +``` + +## `v-model` with Components + +> If you're not yet familiar with Vue's components, you can skip this for now. + +HTML's built-in input types won't always meet your needs. Fortunately, Vue components allow you to build reusable inputs with completely customized behavior. These inputs even work with `v-model`! To learn more, read about [custom inputs](TODO:components.html#Using-v-model-on-Components) in the Components guide.