## Tooltip

Display prompt information for mouse hover.

### Basic usage

Tooltip has 9 placements.

:::demo Use attribute `content` to set the display content when hover. The attribute `placement` determines the position of the tooltip. Its value is `[orientation]-[alignment]` with four orientations `top`, `left`, `right`, `bottom` and three alignments `start`, `end`, `null`, and the default alignment is null. Take `placement="left-end"` for example, Tooltip will display on the left of the element which you are hovering and the bottom of the tooltip aligns with the bottom of the element.
```html
<div class="box">
  <div class="top">
    <el-tooltip class="item" effect="dark" content="Top Left prompts info" placement="top-start">
      <el-button>top-start</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Top Center prompts info" placement="top">
      <el-button>top</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Top Right prompts info" placement="top-end">
      <el-button>top-end</el-button>
    </el-tooltip>
  </div>
  <div class="left">
    <el-tooltip class="item" effect="dark" content="Left Top prompts info" placement="left-start">
      <el-button>left-start</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Left Center prompts info" placement="left">
      <el-button>left</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Left Bottom prompts info" placement="left-end">
      <el-button>left-end</el-button>
    </el-tooltip>
  </div>

  <div class="right">
    <el-tooltip class="item" effect="dark" content="Right Top prompts info" placement="right-start">
      <el-button>right-start</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Right Center prompts info" placement="right">
      <el-button>right</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Right Bottom prompts info" placement="right-end">
      <el-button>right-end</el-button>
    </el-tooltip>
  </div>
  <div class="bottom">
    <el-tooltip class="item" effect="dark" content="Bottom Left prompts info" placement="bottom-start">
      <el-button>bottom-start</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Bottom Center prompts info" placement="bottom">
      <el-button>bottom</el-button>
    </el-tooltip>
    <el-tooltip class="item" effect="dark" content="Bottom Right prompts info" placement="bottom-end">
      <el-button>bottom-end</el-button>
    </el-tooltip>
  </div>
</div>

<style>
  .box {
    width: 400px;

    .top {
      text-align: center;
    }

    .left {
      float: left;
      width: 110px;
    }

    .right {
      float: right;
      width: 110px;
    }

    .bottom {
      clear: both;
      text-align: center;
    }

    .item {
      margin: 4px;
    }

    .left .el-tooltip__popper,
    .right .el-tooltip__popper {
      padding: 8px 10px;
    }

    .el-button {
      width: 110px;
    }
  }
</style>
```
:::


### Theme

Tooltip has two themes: `dark` and `light`。

:::demo Set `effect` to modify theme, and the default value is `dark`.
```html
<el-tooltip content="Top center" placement="top">
  <el-button>Dark</el-button>
</el-tooltip>
<el-tooltip content="Bottom center" placement="bottom" effect="light">
  <el-button>Light</el-button>
</el-tooltip>
```
:::

### More Content

Display multiple lines of text and set their format.

:::demo Override attribute `content` of `el-tooltip` by adding a slot named `content`.
```html
<el-tooltip placement="top">
  <div slot="content">multiple lines<br/>second line</div>
  <el-button>Top center</el-button>
</el-tooltip>
```
:::

### Advanced usage

In addition to basic usages, there are some attributes that allow you to customize your own:

`transition` attribute allows you to customize the animation in which the tooltip shows or hides, and the default value is el-fade-in-linear.

`disabled` attribute allows you to disable `tooltip`. You just need set it to `true`.

In fact, Tooltip is an extension based on [Vue-popper](https://github.com/element-component/vue-popper), you can use any attribute that are allowed in Vue-popper.

:::demo
```html
<template>
  <el-tooltip :disabled="disabled" content="click to close tooltip function" placement="bottom" effect="light">
    <el-button @click="disabled = !disabled">click to {{disabled ? 'active' : 'close'}} tooltip function</el-button>
  </el-tooltip>
</template>

<script>
  export default {
    data() {
      return {
        disabled: false
      };
    }
  };
</script>

<style>
  .slide-fade-enter-active {
    transition: all .3s ease;
  }
  .slide-fade-leave-active {
    transition: all .3s cubic-bezier(1.0, 0.5, 0.8, 1.0);
  }
  .slide-fade-enter, .expand-fade-leave-active {
    margin-left: 20px;
    opacity: 0;
  }
</style>
```
:::


:::tip
The `router-link` component is not supported in tooltip, please use `vm.$router.push`.

Disabled form elements are not supported for Tooltip, more information can be found at [MDN](https://developer.mozilla.org/en-US/docs/Web/Events/mouseenter). You need to wrap the disabled form element with a container element for Tooltip to work.
:::


### Attributes
| Attribute      | Description          | Type      | Accepted Values       | Default  |
|----------------|---------|-----------|-------------|--------|
|  effect   |  Tooltip theme  | string   | dark/light  | dark  |
|  content  | display content, can be overridden by `slot#content` | String   | — | — |
|  placement | position of Tooltip   | string    |  top/top-start/top-end/bottom/bottom-start/bottom-end/left/left-start/left-end/right/right-start/right-end |  bottom |
|  value / v-model | visibility of Tooltip | boolean           | — |  false |
|  disabled       |  whether Tooltip is disabled  | boolean    | — |  false |
|  offset        |  offset of the Tooltip   | number    | — |  0 |
|  transition     |  animation name | string             | — | el-fade-in-linear |
|  visible-arrow   |  whether an arrow is displayed. For more information, check [Vue-popper](https://github.com/element-component/vue-popper) page | boolean | — | true |
|  popper-options        | [popper.js](https://popper.js.org/documentation.html) parameters | Object            | refer to [popper.js](https://popper.js.org/documentation.html) doc | `{ boundariesElement: 'body', gpuAcceleration: false }` |
| open-delay | delay of appearance, in millisecond | number | — | 0 |
| manual | whether to control Tooltip manually. `mouseenter` and `mouseleave` won't have effects if set to `true` | boolean | — | false |
|  popper-class  |  custom class name for Tooltip's popper | string | — | — |
| enterable | whether the mouse can enter the tooltip | Boolean | — | true |
| hide-after | timeout in milliseconds to hide tooltip | number | — | 0 |
| tabindex   | [tabindex](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex) of Tooltip | number | — | 0 |
