javascript - 闭包编译器忽略对象突变

Question

我将以下代码放入高级模式的闭包编译器中:

var obj = (function() {
  /** @constructor */
  function H(a) {
    this.a = a
  }
  var h = new H(1);
  h.b=1
  return h
})();

我返回的结果是:

(function() {
  var a = new function() {
  }(1);
  a.a = 1;
  return a;
})();

为什么它忽略我对对象 h.b=1 所做的更改？

Answer 1

高级编译选项启用 aggressive property removal ，其中包括一些假设:

It makes a strong assumption that properties defined on a "prototype" or "this" will not be iterated over and thus is a candidate for removal.

/** @constructor */
function cls() {
this.x = 1; // removal candidate due to "this" assumption;
}

所以您看到的实际上是 this.a = a 被删除，然后属性 b 被重命名为 a .