关于JavaScript回调函数中`results`参数求值逻辑的技术咨询

Great question—this is a super common point of confusion when you’re first getting comfortable with callbacks, so let’s break it down nice and clearly!

The Core Truth: Parameter Names Are Just Labels #

First off, the name results in your callback function has no special link to the result variable inside addAndHandle. Parameter names are just placeholders you use to refer to values that get passed into the function when it runs. You could name that parameter sum, x, randomName, or even potato—it would still hold the exact same value.

Let’s Walk Through the Code Step by Step #

Let’s trace exactly what happens when your code executes:

1. You call addAndHandle(10, 20, function(results) { console.log(results); }):
   • n1 is set to 10, n2 to 20, and cb gets assigned to that anonymous function you passed in as the third argument.
2. Inside addAndHandle, const result = n1 + n2 calculates 10 + 20 = 30.
3. Then cb(result) runs—this is where you’re invoking the callback function and passing result (which is 30) as its input.
4. When that anonymous callback runs, its first parameter (the one you named results) takes on the value of the argument you just passed in (30). That’s why console.log(results) outputs 30.

A Quick Test to Prove the Name Doesn’t Matter #

If we swap the parameter name for something totally random, it still works perfectly:

addAndHandle(10, 20, function(potato) { 
  console.log(potato); // Still logs 30!
});

The parameter name is just how you refer to the value inside the callback. The actual value comes from whatever you pass to cb() when you trigger the callback.

内容的提问来源于stack exchange，提问作者JavaScriptAssistancePls