[游戏开发]Book.vue，箭头函数不懂。this.book = Books.find((item) =＞ item.id == toParams.id)怎样理解这一段

<template>
    <div>
        <p>图书ID：{{ book.id }}</p>
        <p>书名：{{ book.title }}</p>
        <p>说明：{{ book.desc }}</p>
    </div>
</template>

<script>
import Books from '@/assets/books'
export default {
    data() {
        return {
            book: {}
        }
    },
    created() {
        //this.book = Books.find((item) => item.id == this.$route.params.id);
        this.$watch(
            () => this.$route.params,
            (toParams) => {
                console.log(toParams)
                this.book = Books.find((item) => item.id == toParams.id)
            },
            {
                immediate: true
            }
        )
    }
}
</script>