将树结构转转成数组

By Noxxxx from https://interview.noxxxx.com/?post_type=post&p=106 上山打老虎
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const destruct = (tree, id, pid, children) => {
  
  const flatten = (node) => {
    const result = [];
    const queue = [node];
    
    while(queue.length) {
      const item = queue.shift();
      if (item[children] && item[children].length > 0) {
        item[children].forEach(c => {
          queue.push({
            ...c,
            [pid]: item[id]
          })
        })
      }
        
      delete item[children]
      result.push(item)
    }
    
    return result;
  }
  // 如果是数组而非单个根节点
  if (Array.isArray(tree)) {
    return tree.map(item => flatten(item)).reduce((pre, cur) => pre.concat(cur), [])
  } else {
    return flatten(tree)
  }
}