SOURCE

const treeData = {
    name: '1',
    children: [{
        name: '2',
        children: [{
            name: '4',
            children: []
        }, {
            name: '5',
            children: []
        }]
    }, {
        name: '3',
        children: [{
            name: '6',
            children: []
        }, {
            name: '7',
            children: []
        }]
    }]
}
function getName(data) {
    let ch = data.children
    let length = ch.length
    let result = []
    result.push(data.name)
    if (length) {
        ch.forEach(item => {
            result.push(...getName(item))
        })
    }
    return result
}
function getName2(data) {
    let res = []
    let tem = []
    let queue = [data]
    while (queue.length) {
        tem = queue
        queue = []
        res.push(tem.map(item => {
            if (item.children.length) queue.push(...item.children)
            return item.name
        }))
    }
    return res
}
console.log(getName2(treeData))