d3.js: “Cannot read property 'weight' of undefined” when manually defining both nodes and links for force layout

Question

I tried setting both nodes and links at the same time this way:

var force = d3.layout.force()
    .size([w, h])
    .nodes(nodes)
    .links(connections)
            


        

Answer 1

In addition to the answers mentioning the null in the source/target of links, the reason for this could be the assignment of an out-of-range source/target. E.g. you have 10 nodes and you assign the target to be the 11-th indexed node.