Introduction to three ways of naming javascript functions and their differences_Basic knowledge

Introduction to the three ways of naming JavaScript functions and their differences

First place

Copy code The code is as follows:

function fn(val1,val2) {
alert(val1+val2);
}
fn(1,2);

Second

Copy code The code is as follows:

var fn=function() {
alert(val1+val2);
}
fn(1,2);

Third

Copy code The code is as follows:

var fn=new Function("alert(val1+val2)");
fn(1,2);

The above three methods are logically equivalent, but there are still some small differences: Difference 1: The function in Example 1 will be loaded into the scope before the code is executed, while in Example 2 it will be loaded into the scope after the code is executed. There will be a definition only when it is one line; Difference 2: The function declaration will assign a name to the function, while the function expression creates an anonymous function and then assigns the anonymous function to a variable; Difference 3: Example 3 uses Function() Constructor clone functions are generally rarely used because a function usually consists of multiple statements. If they are passed as parameters in the form of strings, it will inevitably make the code less readable.

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