```js
var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
function Node(value) {
this.value = value;
this.left = null;
this.right = null;
}
function BinarySearchTree() {
this.root = null;
this.remove = function(value) {
if (this.root === null) {
return null;
}
var target;
var parent = null;
// find the target value and its parent
(function findValue(node = this.root) {
if (value == node.value) {
target = node;
} else if (value < node.value && node.left !== null) {
parent = node;
return findValue(node.left);
} else if (value < node.value && node.left === null) {
return null;
} else if (value > node.value && node.right !== null) {
parent = node;
return findValue(node.right);
} else {
return null;
}
}).bind(this)();
if (target === null) {
return null;
}
// count the children of the target to delete
var children = (target.left !== null ? 1 : 0) + (target.right !== null ? 1 : 0);
// case 1: target has no children
if (children === 0) {
if (target == this.root) {
this.root = null;
}
else {
if (parent.left == target) {
parent.left = null;
} else {
parent.right = null;
}
}
}
// case 2: target has one child, change code below this line
};
}
```
### After Test
```js
console.info('after the test');
```
## Solution