What is an anonymous callback? What is the difference between it and callback function? (with detailed explanation)

The previous article introduced you to "What is a closure function?" What is the role of closure function? (Attached code) ", this article continues to introduce to you what is an anonymous callback? What is the difference between it and callback function? (Detailed explanation attached), come on, let’s work hard together!

Anonymous callback format:

Call function (pass in your specified function)

The difference between callback functions:

1. The callback function passed in as a string

2.The callback function passed in as an anonymous function

3. The callback passed in the character-rich method is still counted. This function can be used multiple times and called arbitrarily, because this is a pre-loaded ordinary function. The callback function passed in the fixed-name function

Can only be used in the current callback function and cannot be used elsewhere.

4. The effect of returning an anonymous function to a function is high, because after the callback function is run, the anonymous function is recycled, and the function passed in as a string is a pre-loaded ordinary function

number, so when the page has not been executed, it will never be sold.

Take the code display as an example:

First, we still define a function function js(), and then output the variable function we defined, Before we made the callback function, we also first defined a function function jia(), then (return) returned the value of no1 no2, then called introduction(), and then passed the string to js. When we perform code operations, we will get The result we just entered; the above is the callback function we made before;

When we directly use $jia to define function() and return (return $no1 $no2), we are defining an anonymous function at this time , we directly assign the function to the $jia variable, and then, we pass the $jia variable through js, which is an anonymous callback.

The specific code is as follows:

';
$jia =  function ($no1, $no2){
    return $no1 + $no2;
    };
    //匿名回调
    js($jia);
?>

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