How to load data from a CSV file in D3 v5

问题

I'm trying to load data from a CSV file in D3; I have this code:

function update (error, data) {
    if (error !== null) {
        alert ("Couldn't load the dataset!");
    } else {
        //do something
    };

function changeData () {
    d3.csv ("data/dataset.csv", update);
}

If I use D3 v4 it works fine, but if I switch to v5 it doesn't work anymore. Can someone explain to me how to modify the code to make it work with D3 v5?

回答1:

d3 v5 uses the fetch API and returns a promise requiring the below code.

d3.csv('yourcsv.csv')
  .then(function(data) {
      // data is now whole data set
      // draw chart in here!
  })
  .catch(function(error){
     // handle error   
  })

In case in the future people want v4. d3 v4 on the other hand uses the XMLHttpRequest method, and does not return a promise requiring this code

d3.csv('yourcsv.csv', function(data) {
    //whole data set
    // draw chart here
})

csv loading is async so make sure to run your chart code within the csv function.

回答2:

@pmkro's answer is good, but if you want to use ES7 async/await instead of Promise.then:

async function doThings() {
  const data = await d3.csv('yourcsv.csv');
  // do whatever with data here
}

doThings();

来源：https://stackoverflow.com/questions/58093568/text-and-arc-not-visible-d3