# Async Single ```html ``` ```js function genChildren (option) { const children = [] for (let i = 0; i <= option.depth; ++i) { children.push({ label: option.label + '_' + i, value: option.label + '_' + i, isLeaf: option.depth === 3 }) } return children } const options = [ { label: 'Root', value: 'root', isLeaf: false } ] export default { data () { return { value: null, options: options } }, methods: { handleLoad (option, resolve) { window.setTimeout(() => { resolve(genChildren(option)) }, 1000) } } } ```