JavaScript对象未实例化
JavaScript对象未实例化
提问于 2019-11-23 07:36:17
我有一个类dynObj，但它的独立实例似乎采用了最近定义的实例的值。
draw() {
tmov1 = new dynObj(args...); //Displays as a white ball on webpage, as intended
tmov2 = new dynObj(different args...); //Seemingly overwrites the properties of tmov1
objects.push(tmov1, tmov2)
for (var i in objects) {
objects[i].dostuff() //Normally causes the object to display as intended,
}; //but will only ever display one
};dynObj类如下所示：
class baseObj {
constructor(position, dimentions, properties) {
this.pos = createVector(position.x,position.y) || null;
this.shape = properties.shape
if (this.shape == "ellipse") {
this.dim = dimentions || {diam:0}
} else if (this.shape == "quadrilateral") {
this.dim = dimentions || { x: 0, y: 0 };
}
};
};
class dynObj extends baseObj {
constructor(position, dimentions, suvat, properties) {
super(position, dimentions, properties);
self = this
self.type = 'dynamic'
self.properties = properties
//more definitions with self.x = someval
};
getDistance(a,b){
if (a == undefined || b == undefined) return false;
var dist = p5.Vector.sub(b,a)
//console.log(dist)
return dist
};
tick(ticksize) {
self.assignLastTick(function(lasttick){
self.lasttick = lasttick
self.time = self.time + ticksize
self.updateSuvat(ticksize)
})
};
//assorted methods...
}为什么实例会相互影响？(如果需要更多上下文，可以在实际操作中提供此链接)
Stack Overflow用户
回答已采纳
发布于 2019-11-23 07:45:31
问题是，您正在创建一个全局变量self，并使用它而不是this。所有实例都访问相同的全局变量，该变量包含创建的最后一个对象的this值。
在tick()的回调函数中，您需要一种方法来引用原始对象，因此您需要在那里绑定一个局部变量self，而不是使用全局变量。请参阅How to access the correct this inside a callback?
class dynObj extends baseObj {
constructor(position, dimentions, suvat, properties) {
super(position, dimentions, properties);
this.type = 'dynamic'
this.properties = properties
//more definitions with this.x = someval
};
getDistance(a,b){
if (a == undefined || b == undefined) return false;
var dist = p5.Vector.sub(b,a)
//console.log(dist)
return dist
};
tick(ticksize) {
let self = this;
this.assignLastTick(function(lasttick){
self.lasttick = lasttick
self.time = self.time + ticksize
self.updateSuvat(ticksize)
})
};
//assorted methods...
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/59003138
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