不过又发现一个es6转成es5后的bug:
下面es6的代码：
class A {
constructor() {
this.x = 1;
}
}
class B extends A {
constructor() {
super();
this.x = 2;
super.x = 3;
console.log(this.x,super.x); // 3
}
}
let b = new B();
可以看出在浏览器中直接执行结果为：3 undefined
以上同样的代码，通过Creator运行之后结果确实2 undefined,
所以我去quick文件夹中特定查看了转成es5以后的代码如下，并执行了结果也如下：
<script>
"use strict";
var _get = function get(object, property, receiver) {
if (object === null) object = Function.prototype;
var desc = Object.getOwnPropertyDescriptor(object, property);
if (desc === undefined) {
var parent = Object.getPrototypeOf(object);
if (parent === null) {
return undefined;
} else {
return get(parent, property, receiver);
}
} else if ("value" in desc) {
return desc.value;
} else {
var getter = desc.get;
if (getter === undefined) {
return undefined;
}
return getter.call(receiver);
}
};
var _set = function set(object, property, value, receiver) {
var desc = Object.getOwnPropertyDescriptor(object, property);
console.log("desc:",desc);
if (desc === undefined) {
var parent = Object.getPrototypeOf(object);
console.log("parent:",parent);
if (parent !== null) {
set(parent, property, value, receiver);
}
} else if ("value" in desc && desc.writable) {
desc.value = value;
} else {
var setter = desc.set;
if (setter !== undefined) {
setter.call(receiver, value);
}
}
return value;
};
var _createClass = function() {
function defineProperties(target, props) {
for (var i = 0; i < props.length; i++) {
var descriptor = props[i];
descriptor.enumerable = descriptor.enumerable || false;
descriptor.configurable = true;
if ("value" in descriptor) descriptor.writable = true;
Object.defineProperty(target, descriptor.key, descriptor);
}
}
return function(Constructor, protoProps, staticProps) {
if (protoProps) defineProperties(Constructor.prototype, protoProps);
if (staticProps) defineProperties(Constructor, staticProps);
return Constructor;
};
} ();
var _class;
function _classCallCheck(instance, Constructor) {
if (! (instance instanceof Constructor)) {
throw new TypeError("Cannot call a class as a function");
}
}
function _possibleConstructorReturn(self, call) {
if (!self) {
throw new ReferenceError("this hasn't been initialised - super() hasn't been called");
}
return call && (typeof call === "object" || typeof call === "function") ? call: self;
}
function _inherits(subClass, superClass) {
if (typeof superClass !== "function" && superClass !== null) {
throw new TypeError("Super expression must either be null or a function, not " + typeof superClass);
}
subClass.prototype = Object.create(superClass && superClass.prototype, {
constructor: {
value: subClass,
enumerable: false,
writable: true,
configurable: true
}
});
if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass;
}
var A = function A() {
_classCallCheck(this, A);
this.x = 1;
};
var B = function(_A) {
_inherits(B, _A);
function B() {
_classCallCheck(this, B);
var _this2 = _possibleConstructorReturn(this, (B.__proto__ || Object.getPrototypeOf(B)).call(this));
_this2.x = 2;
_set(B.prototype.__proto__ || Object.getPrototypeOf(B.prototype), "x", 3, _this2);
console.log(_this2.x, _get(B.prototype.__proto__ || Object.getPrototypeOf(B.prototype), "x", _this2));
return _this2;
}
return B;
} (A);
var b = new B();
console.log("b",b);
</script>
可以看出结果确实为:2 undefined
可以看出同样的代码，执行的结果却不同。。。
我通过代码打断点查看了这个es5之后的代码super.x = 3语句，在es5中执行的结果就等于什么都没做，有兴趣的同学可以自己试试。
（我不知道ccc中是如何把es6转es5的，如有大神知道，烦请告知。。。谢谢）
总结：在ccc中使用es6编写代码时，尽量避免使用super.属性的方式取值赋值，一般不会出现这种意想不到的bug。
