Delete nodes in a Graph not working perfectly in js

I have created a graph which containing key and value pair ,key is for node number and value for adjacency list value which is an array of adjacent edges, here I wrote a function that will delete the node and adjacency edges in the graph, but here the function is not working ,which thing should I have to modified here that I want graph like {1:[2,4],2:[1,3],3:[1,4]} code is given below

var graph = {
    1: [2, 4],
    2: [1, 3],
    3: [2, 4],
    4: [1, 4]
  };
function deleteNode(key){
    if(!graph[key]){
      return;
    }else{
      graph[key].splice(key, 1);
    }
  }
  deleteNode(3)
  console.log(graph);

If you want to remove node 3, the result should not have any mention of 3 in it anymore. For the example graph the expected result should be:

{
    1: [2, 4],
    2: [1],
    4: [1, 4],
}

So in your code you would have to first iterate all the neighbors of the node, and remove the node from their adjacency lists. And then delete the node itself:

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

function deleteNode(key){
    if (!graph[key]) return;
    // Remove any edge that connects to this node
    for (const neighbor of graph[key]) {
        graph[neighbor] = graph[neighbor].filter(target => target != key);
    }
    // Remove the node itself
    delete graph[key];
}

const graph = {
    1: [2, 4],
    2: [1, 3],
    3: [2, 4],
    4: [1, 4]
};
deleteNode(3)
console.log(graph);

<!-- end snippet -->

Don't try to shift the keys in situ

It is better to build a new object, with the unwanted key removed.

A few other pointers:

• Remember that your keys are in fact strings, even if you did not intend that; so you must delete "3" not 3

• Rather than mutating a global variable it is clearer for your function to receive a value of graph and return a new value.

• Your expected result does not make much sense yet - presumably you are planning to separately amend the lists to "rename" the values that have moved, and delete the one that has been deleted?

• When you do that you will realise how annoying it is to have keys as strings and yet list entries as numbers. Maybe you should switch to a different design, that uses arrays of arrays, i.e. always starting at 0?

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

var graph = {
  1: [2, 4],
  2: [1, 3],
  3: [2, 4],
  4: [1, 4]
};

function deleteNode(graph, keyToDelete) {
  const oldKeys = Object.keys(graph)
  const listsToKeep = Object.entries(graph).filter(([key, list]) => key !== keyToDelete).map(([key, list]) => list)
  const newLen = Object.values(listsToKeep).length
  const newKeys = oldKeys.slice(0, newLen)

  return Object.fromEntries(
    newKeys.map(
      (key, i) => [key, listsToKeep[i]]
    )
  )

}
graph = deleteNode(graph, "3")
console.log(graph);

<!-- end snippet -->