SOURCE

// 反转二叉树

function revertTree(root) {
    if (root) {
        [root.left, root.right] = [root.right, root.left];

        revertTree(root.left);
        revertTree(root.right);
    };

    return root;
}


var tree = {
  value: 1,
  left: {
    value: 2,
    left: {
      value: 4
    }
  },
  right: {
    value: 3,
    left: {
      value: 5,
      left: {
        value: 7
      },
      right: {
        value: 8
      }
    },
    right: {
      value: 6
    }
  }
}

// console.log(revertTree(tree));


function revertTree(root) {
    if (root) {
        [root.left, root.right] = [root.right, root.left];

        revertTree(root.left);
        revertTree(root.right)
    }

    return root;
}

function Mirror(node){
    if(!node){
      throw new Error('empty tree')
    }

    var queue = [];
    queue.push(node);

    while(queue.length !== 0) {
   // 1 先进先出，但不要node = queue.shift(),否则return node为undefined
      var current = queue.shift();
      
      if(current) {
        // 2 交换左右节点
        var temp = current.left;
        current.left = current.right;
        current.right = temp;
		 
        if (current.left) queue.push(current.left)
        if (current.right) queue.push(current.right);
      }  
      
    } 
    
    // 3 返回反转后的tree
    return node
}

var invertTreeMinor = function(root) {
    
    let stack = [root];
    let current = null;
    let temp = null;
    while( current = stack.pop() ){
        temp = current.right;
        current.right =  current.left;
        current.left = temp;
        if (current.right) {
                stack.push(current.right);   
        }
        if (current.left) {
            stack.push(current.left);   
        }
        
    }
    return root
};
console.log('origin', invertTreeMinor(tree));

var invertTree = function(root) {
    var queue = [];
    queue.push(root);
    var curNode = null;
    while((curNode = queue.shift()) != null){
        //switch curNode left and right
        // var tmp = curNode.left;
        // curNode.left = curNode.right;
        // curNode.right = tmp;

        [curNode.left, curNode.right] = [curNode.right, curNode.left];
        if (curNode.left !== null){
            queue.push(curNode.left);
        }
        if (curNode.right !== null){
            queue.push(curNode.right);
        }
    }
    return root;
};

// console.log('new', invertTree(tree));