我想让这段代码变得更简单：
links.forEach(function(link) {
link.source = nodes[link.source] ||
(nodes[link.source] = {
name: link.source
});
link.target = nodes[link.target] ||
(nodes[link.target] = {
name: link.target
});
console.log(nodes)
});
所以，我这样重构它：
links.forEach(function(link) {
if (nodes[link.source] == null) {
nodes[link.source] = {
name: link.source
};
} else if (nodes[link.target] == null) {
nodes[link.target] = {
name: link.target
};
} else {
console.log('Not problem');
}
});
但是，现在我收到此错误：
无法读取未定义的属性“push”
这是完整的原始代码：
<DOCTYPE html>
<meta charset="utf-8">
<style>
.node {
fill: #4D00DD;
stroke: #fff;
stroke-width: 2px;
}
.link {
stroke: #777;
stroke-width: 8px;
}
</style>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script>
var width = 1080,
height = 960;
var links = [
{ source : "Baratheon", target : "Lannister"},
{ source : "Baratheon", target : "Stark"},
{ source : "Lannister", target : "Stark"},
];
var nodes = {};
// parse links to nodes
links.forEach(function(link) {
link.source = nodes[link.source] ||
(nodes[link.source] = {name: link.source});
link.target = nodes[link.target] ||
(nodes[link.target] = {name: link.target});
console.log(nodes)
});
// add svg to our body
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
var force = d3.layout.force()
.size([width, height])
.nodes(d3.values(nodes))
.links(links)
.on("tick", tick)
.linkDistance(600)
.start();
var link = svg.selectAll(".link")
.data(links)
.enter().append("line")
.attr("class", "link")
var node = svg.selectAll(".node")
.data(force.nodes())
.enter().append("circle")
.attr("class", "node")
.attr("r", width * 0.03);
function tick(e) {
node.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; })
.call(force.drag);
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; })
}
</script>
