document 写法

# UfsProgressBar

## Component Info
A progress bar component of specified progress.

## Usage
```
<ufs-progress-bar :rate="20"></ufs-progress-bar>
```

## Arguments
Param | Type | Default | Details
----- | ---- | ------ | ----
rate | `Number` | | Rate of progress.

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# BackToTop

## Usage
```
<ufs-back-to-top></ufs-back-to-top>
```

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# BestSellerGift

## Usage
```
<ufs-best-seller-gift :best-seller-gift="bestSellerGift"></ufs-best-seller-gift>
```
```
data () {
return {
bestSellerGift: {
url: 'XXXXXX',
score: XXX,
name: 'XXXXXXXX'
}
}
}
```

## Arguments
Param | Type | Default | Details
----- | ---- | ------- | -------
url | `String` | | The src of gift image
score | `Number` | | Score of gift
name | `String` | | Name of gift

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