如何访问 D3 回调中的当前选择? [英] How can I get access to the current selection inside a D3 callback?

问题描述

如何在 D3 回调中访问当前选择?

How can I get access to the current selection inside a D3 callback?

group.selectAll('.text')
    .data(data)
    .enter()
    .append('text')
    .text((d) => d)
    .attr('class', 'tick')
    .attr('y', (d) => {
      // console.log(this) <-- this gives me window :( but I want the current selection or node: <text>
      return d
    })

我可以在回调中做一个 d3.select('.tick') ，因为那时我已经添加了一个类并且可以通过 d3.select 获取节点，但是如果我没有添加课程?

I could do a d3.select('.tick') in the callback, since by then I've added a class and can get the node via d3.select, but what if I didn't add the class?

推荐答案

这里的问题是使用箭头函数来访问this.

The problem here is the use of an arrow function to access this.

应该是:

.attr("y", function(d){
    console.log(this);
    return d;
})

在此处查看有关 this 的箭头函数的文档:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

See here the documentation about arrow functions regarding this: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

它说:

与函数表达式相比，箭头函数表达式的语法更短，并且在词法上绑定了 this 值(不绑定自己的 this、arguments、super 或 new.target).

An arrow function expression has a shorter syntax compared to function expressions and lexically binds the this value (does not bind its own this, arguments, super, or new.target).

要在箭头函数中获取当前 DOM 元素 this，请结合使用第二个和第三个参数:

To get the current DOM element this in an arrow function, use the second and third arguments combined:

.attr("y", (d, i, n) => {
    console.log(n[i]);
    return n[i];
})

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