Updating links on a force directed graph from dynamic json data

Well I could find the solution browsing through, posting it here for anyone needing help on this topic. The idea is to create an object of the graph and playing around with the nodes and links arrays.
The JS code goes as:

var graph;
function myGraph(el) {

// Add and remove elements on the graph object
this.addNode = function (id) {
    nodes.push({"id":id});
    update();
};

this.removeNode = function (id) {
    var i = 0;
    var n = findNode(id);
    while (i < links.length) {
        if ((links[i]['source'] == n)||(links[i]['target'] == n))
        {
            links.splice(i,1);
        }
        else i++;
    }
    nodes.splice(findNodeIndex(id),1);
    update();
};

this.removeLink = function (source,target){
    for(var i=0;i<links.length;i++)
    {
        if(links[i].source.id == source && links[i].target.id == target)
        {
            links.splice(i,1);
            break;
        }
    }
    update();
};

this.removeallLinks = function(){
    links.splice(0,links.length);
    update();
};

this.removeAllNodes = function(){
    nodes.splice(0,links.length);
    update();
};

this.addLink = function (source, target, value) {
    links.push({"source":findNode(source),"target":findNode(target),"value":value});
    update();
};

var findNode = function(id) {
    for (var i in nodes) {
        if (nodes[i]["id"] === id) return nodes[i];};
};

var findNodeIndex = function(id) {
    for (var i=0;i<nodes.length;i++) {
        if (nodes[i].id==id){
            return i;
        }
        };
};

// set up the D3 visualisation in the specified element
var w = 500,
    h = 500;
var vis = d3.select("#svgdiv")
    .append("svg:svg")
    .attr("width", w)
    .attr("height", h)
    .attr("id","svg")
    .attr("pointer-events", "all")
    .attr("viewBox","0 0 "+w+" "+h)
    .attr("perserveAspectRatio","xMinYMid")
    .append('svg:g');

var force = d3.layout.force();

var nodes = force.nodes(),
    links = force.links();

var update = function () {
      var link = vis.selectAll("line")
        .data(links, function(d) {
            return d.source.id + "-" + d.target.id; 
            });

    link.enter().append("line")
        .attr("id",function(d){return d.source.id + "-" + d.target.id;})
        .attr("class","link");
    link.append("title")
    .text(function(d){
        return d.value;
    });
    link.exit().remove();

    var node = vis.selectAll("g.node")
        .data(nodes, function(d) { 
            return d.id;});

    var nodeEnter = node.enter().append("g")
        .attr("class", "node")
        .call(force.drag);

    nodeEnter.append("svg:circle")
    .attr("r", 16)
    .attr("id",function(d) { return "Node;"+d.id;})
    .attr("class","nodeStrokeClass");

    nodeEnter.append("svg:text")
    .attr("class","textClass")
    .text( function(d){return d.id;}) ;

    node.exit().remove();
    force.on("tick", function() {

        node.attr("transform", function(d) { return "translate(" + d.x + "," + d.y         + ")"; });

        link.attr("x1", function(d) { return d.source.x; })
          .attr("y1", function(d) { return d.source.y; })
          .attr("x2", function(d) { return d.target.x; })
          .attr("y2", function(d) { return d.target.y; });
    });

    // Restart the force layout.
    force
    .gravity(.05)
    .distance(50)
    .linkDistance( 50 )
    .size([w, h])
    .start();
};


// Make it all go
update();
}

function drawGraph()
{
graph = new myGraph("#svgdiv");
graph.addNode('A');
graph.addNode('B');
graph.addNode('C');
graph.addLink('A','B','10');
graph.addLink('A','C','8');
graph.addLink('B','C','15');
}