d3.json（）和JSON.parse（）会产生相同的结果吗？

Question

I am having an issue moving from loading an external JSON file to using a local json string. At first, it seemed like d3.json() returned the same JSON array that I got using JSON.parse() inside of a $.getJSON(), although, while they seem similar, it looks like d3.json added an "ID" variable to my JSON data. Which seems pretty important when constructing a Sankey Graph in D3 . Also, using the exact same data, with $.getJSON() and JSON.parse(), this ID element is not present in the exact same output calls. Does D3 purposely add an "ID" element to its data? How do I achieve the same result with JSON.parse()?

So visually, the output of a console.log(mygraph) call appears like:

    Object {source: Object, target: Object, value: "0", path: "path#0", dy: 0}
    dy:0
    id:0
    path:"path#3"
    source:Object
    sy:0
    target:Object
    ty:0
    value:"0"
    __proto__:Object

But, the latter method with a console.log(mygraph) call appears like:

    Object {source: Object, target: Object, value: "0", path: "path#0", dy: 0}
    dy:0
    path:"path#3"
    source:Object
    sy:0
    target:Object
    ty:0
    value:"0"
    __proto__:Object

What exactly is this "ID" and how do I get it using the latter method? Actually, how do I load a local JSON variable into D3?

Answer 1

d3.json() is like $.getJSON() , in that it takes a url string as the 1st param, and a function called when the data is loaded as 2nd param.

JSON.parse() does something else. It takes a string that looks like JSON and parses it into javascript objects like json.

Neither one will add anything such as an id param to the data it produces. id would have to be in the data you're loading/parsing.

One thing that might have happened to produce id is that you successfully loaded/parsed your data, then passed the it to another function that added the id prop. In that case, it's even possible that some of your confusion occurred from the way Chrome's console.log lets you expand whatever object you logged. The thing is that even if you console.log 'ed your object BEFORE some other function added the id prop to it, BY THE TIME you clicked to expand it, it was already there and showed up.