javascript Javascript调用父函数
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Javascript call parent function
提问by Ilya Gazman
Question inside the description
描述中的问题
function Parent(){
this.alertParent(){
alert("Parent alert");
}
function child(){
// how can I call to this.alertParent() from here without passing any
// parameters?
}
}
回答by Felix Kling
The title of your question is confusing. The informal term "parent" function is rather used for the callingfunction.
你的问题标题令人困惑。非正式术语“父”函数用于调用函数。
In your case, you have two functions inside a constructor function and you just want to call one from the other. Specifically, you want to call a "public" method from a "private" method (I put these terms in quotes since JavaScript does not support visibility and these are workaround to achieve the same).
在您的情况下，您在构造函数中有两个函数，而您只想从另一个调用一个。具体来说，您希望从“私有”方法调用“公共”方法（我将这些术语放在引号中，因为 JavaScript 不支持可见性，而这些是实现相同目的的变通方法）。
Just keep a reference to the current instance:
只需保留对当前实例的引用：
function Parent(){
var self = this;
this.alertParent = function() {
alert("Parent alert");
}
function child() {
self.alertParent();
}
}
childcloses over all variables in the context it is defined, so it as access to self. thisof course changes [MDN].
child关闭它定义的上下文中的所有变量，因此它可以访问self. this当然改变[MDN]。
Instead of creating a closure, you can also pass the instance explicitlyto child, using either .call()[MDN]or .apply()[MDN].
除了创建闭包，您还可以使用[MDN]或[MDN]将实例显式传递给。child.call().apply()
So your function definition stays
所以你的函数定义保持不变
function child() {
this.alertParent();
}
and when you call the function, you call it, e.g. with child.call(this)if you know that thisrefers to your instance (instead of thisit can be any other variable).
并且当您调用该函数时，您会调用它，例如，child.call(this)如果您知道它this指的是您的实例（而不是this它可以是任何其他变量）。
回答by xdazz
Your code has syntax error. Maybe you means this:
您的代码有语法错误。也许你的意思是：
function Parent(){
this.alertParent = function () {
alert("Parent alert");
};
this.child = function () {
this.alertParent();
}
}
