问题
If the parent and iframe were both on the same domain, we can call a function of the parent window from iframe:
iframe code:
// here we call 'myFunction' which is a parent function
window.postMe = "postMe value here";
window.parent.myFunction(postMe);
In the parent window, we can define a function like this:
function myFunction(postMe) {
    ((console&&console.log)||alert)("postMe= " + postMe);
}
And the code above logs the "postMe" value correctly.
But my question is how can I call the function of iframe from parent.
To be more clear I want this code on my iframe:
 function myFunction(postMe) {
        ((console&&console.log)||alert)("postMe= " + postMe);
    }
then I want to be able to call myFunction(postMe); on the parent ... 
Note: I can't select the iframe like HTMLIFrameElement.contentWindow or window.frames['name'] for some reasons. 
The final goal is: I want to pass a variable multiple times and every time I want from parent to the iframe. @CertainPerformance has a solution for this that I can't make it work.
iframe code:
window.postMeToParent= "post me to parent";
window.parent.myFunction(postMeToParent, (response) => {
  console.log(response);
});
parent code:
function myFunction(postMeToParent, callback) {
  const postMeToiframe= "post me to iframe";
  // do something with postMeToiframe in parent:
  ((console&&console.log)||alert)(postMeToParent);
  // do something with postMeToiframe in child:
  callback(postMeToiframe);
}
The problem is it only can be run via iframe and I can't call the function and pass variables from parent.
回答1:
You can pass the function object from iframe to parent function and invoke from there.
On the parent:
function tunnel(fn){
     fn('postMe');
}
On the iframe:
function myFunction(postMe) {
     ((console&&console.log)||alert)("postMe= " + postMe);
}
window.parent.tunnel(myFunction);
If your parent document will not be loaded at that point, try using below
var parentDocument = window.parent.document; 
$( parentDocument ).ready(function() { 
     window.parent.tunnel(myFunction); 
}
来源:https://stackoverflow.com/questions/56456068/how-can-i-call-the-function-of-iframe-from-parent