SOURCE

//深度优先遍历方法

let tree =  {
    id: '1',
    title: '节点1',
    children: [
      {
        id: '1-1',
        title: '节点1-1'
      },
      {
        id: '1-2',
        title: '节点1-2',
        children: [{
          id: '2',
          title: '节点2',
          children: [
            {
              id: '2-1',
              title: '节点2-1'
            }
          ]
        }]
      }
    ]
  }
  
  let widthTraversal3 = (node) => {
    let nodes = []
    let stack = []

    if(node){
      stack.push(node)
      while(stack.length){
        let item = stack.shift()
        let children = item.children
        nodes.push(item.id)
        if(children){
           for(var i=0;i<children.length;i++){
            stack.push(children[i])
           }
        }
      }
    }

    return nodes
  }

console.log(widthTraversal3(tree))