connectivity.js

var vertices = [];
var edges = [];

vertices.push("A");
vertices.push("B");
vertices.push("C");
vertices.push("D");
vertices.push("E");

edges.push(["A", "B"]);
edges.push(["A", "C"]);
edges.push(["B", "D"]);
edges.push(["D", "C"]);



function getChildren(vertex){
    var result = [];
    for(var i = 0; i < edges.length; i++){
        if(edges[i][0] == vertex){
            result.push(edges[i][1]);
        }
        if(edges[i][1] == vertex){ // JSM - remove this if you want it to be directed graph
            result.push(edges[i][0]);
        }
    }
    return result;
}

function getUnvisitedChildren(vertex, visitList){
    var result = [];
    var children = getChildren(vertex);
    for(var j = 0; j < children.length; j++){
        if(visitList.indexOf(children[j]) < 0){
            result.push(children[j]);
        }
    }
    return result;
}

var visitList = [];

function getUnreachableNodes(root){
    var queue = [];
    var visitList = [];
    queue.push(root);
    while(queue.length > 0){
        var next = queue.shift();
        if(visitList.indexOf(next) < 0){
            visitList.push(next);
            queue = queue.concat(getUnvisitedChildren(next, visitList));
        }
    }
    var missingList = [];
    for(var i = 0; i < vertices.length; i++){
        if(visitList.indexOf(vertices[i]) < 0){
            missingList.push(vertices[i]);
        }
    }
    return missingList;
}

function testConnectivity(root){
    var nodes = getUnreachableNodes(root);
    if(nodes.length > 0){
        console.log("Graph is NOT fully connected");
        for(var i = 0; i < nodes.length; i++){
            console.log(nodes[i] + " could not be reached");
        }
    } else{
        console.log("Graph is fully connected")
    }
}

testConnectivity("A");
testConnectivity("E");