Uncaught TypeError: d3.csv(…).then is not a function

问题

    var allData;
    d3.csv('hello.csv', function(d) {
      return {
        id: +d.id,
        state: d.state
      };
    }).then(function(data) {
      allData = data;
    });

Above code is causing an error

Uncaught TypeError: d3.csv(...).then is not a function

I don't know what is wrong.

来源：https://stackoverflow.com/questions/60625450/uncaught-typeerror-d3-csv-then-is-not-a-function