I am dealing the D3.js and I found a code which I would like to use but I don't understand what happens there. I looked up what the "force" things do but on websites it always said that it can manipulate links physically but not code-wise.

var linkForce = d3
.forceLink()
.id(function (link) { return link.id })
.strength(function (link) { return link.strength })

 var simulation = d3
.forceSimulation()
.force('link', linkForce)
.force('charge', d3.forceManyBody().strength(-120))
.force('center', d3.forceCenter(width / 2, height / 2))

I would be glad if you can help me out :)