How to use better scroll the element when the parameter is a letter

In my webApp project, I want to click a letter, and the relative content will be scrolled to display.
Here is js code:

<script>
import Bscroll from 'better-scroll'
export default
name: 'CityList',
props:
cities: Object,
hotCities: Array,
letter: String
,
watch:
letter ()
if (this.letter)
const element = this.$refs[this.letter][0]
this.scroll.scrollToElement(element)


,
mounted ()
this.scroll = new Bscroll(this.$refs.wrapper)


</script>


I used vue 2.9.3
But I got a error:

[Vue warn]: Error in callback for watcher "letter": "TypeError: Cannot read property '0' of undefined"


who can help me?

<div
class="area"
v-for="(item, key) of cities"
:key="key"
>
<div class="title border-topbottom">key</div>
<div class="item-list">
<div
class="item border-bottom"
v-for="innerItem of item"
:key="innerItem.id"
>
innerItem.name
</div>
</div>
</div>


I should add :ref="key"

<div
class="area"
v-for="(item, key) of cities"
:key="key"
:ref="key"
>


1 Answer
1

I think there is a time when watch function run, this.$refs[this.letter] is not available yet. So you might want to check:

this.$refs[this.letter]

watch:
letter ()
if (this.letter && this.$refs[this.letter])
const element = this.$refs[this.letter][0]
this.scroll.scrollToElement(element)





Your cities has different ref, you don't need to access [0] element

cities

watch:
letter ()
if (this.letter && this.$refs[this.letter])
const element = this.$refs[this.letter]
this.scroll.scrollToElement(element)





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