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Nested functions are allowed in javascript:
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Remember this:
Nesting is actually a kind of loop. There are two handles in the loop to let us grasp: one is the termination condition and the other is the increment.
Nested functions are a little different from normal functions:
Since it is a nested function, it is to apply itself as a value to the function body. This requires the function to have a return value. The return statement is required.
Example:
Example 1:
Copy codeThe Code is as follows:
Function a (x ){
If (x <= 1) return 1;
Else return x * a (x-1 );
}
Example 1 is a nested function. Let's look at two handles: if (x <= 1) return 1; this is the condition for termination when x <= 1, else return x * a (x-1); this is incremental, and the parameter is reduced by 1 each nested call to function.
So this example can also be converted into a circular body as in example 2.
Example 2:
Copy codeThe Code is as follows:
Function a (x ){
If (x <= 1) return 1;
Else {
Var m = 1;
For (var I = 2; I <= x; I ++ ){
M * = I;
}
Return m;
}
}
As shown in example 2, nested functions implement such a loop.
Example 3:
Copy codeThe Code is as follows:
Function a (x ){
If (x <= 1) return 1;
Else {
X --;
Return (x + 1) * a (x );
}
}
For example 3, as long as we have identified two handles in the nested function, the nested function can be implemented wherever it is put. Obviously, this is not as good as Example 1.
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