在拖动事件的函数中访问“this”

I have the following code for a drag event:

我有以下拖动事件的代码:

BusinessProductFigure.prototype = new Figure();
BusinessProductFigure.prototype.constructor = BusinessProductFigure;
BusinessProductFigure.prototype.addTo = function(c, x0, y0, id) {
console.log("this=",this);
var n = d3.select(this);
var wasMoved = false;
var dragger = d3.behavior.drag()
    .origin(function(d){return d;})
    .on("drag", this.move)
    .on("dragend", dropHandler)

The function this.move executes in the above code and performs it's designated function. However, I want to add a function that is called upon on drag event. I tried the following:

这个函数。move在上面的代码中执行并执行指定的功能。但是，我想添加一个在拖动事件上调用的函数。我试着以下:

BusinessProductFigure.prototype.addTo = function(c, x0, y0, id) {
console.log("this=",this);
var n = d3.select(this);
var wasMoved = false;
var dragger = d3.behavior.drag()
    .origin(function(d){return d;})
    .on("drag", function(){wasMoved=true; this.move})
    .on("dragend", dropHandler)

But the above code does not calls the move function. How can I access 'this' property inside the function?

但是上面的代码不调用move函数。如何访问函数中的“this”属性?

2 个解决方案

#1

You can bind relevant context using bind(), and use parenthensis to call the method:

您可以使用bind()绑定相关上下文，并使用括号调用方法:

.on("drag", function(){wasMoved=true; this.move()}.bind(this))

内(“拖”,函数(){ wasMoved = true;this.move()} .bind(这))

#2

Another solution because it's 2016 already is to use arrow function to preserve lexical context:

由于2016年已经到来，另一个解决方案是使用箭头函数来保存词汇上下文:

.on("drag", () => {
   wasMoved = true;
   this.move()
})

#1