JavaScript code optimization

Javascript Optimization

1,

If (otest! = Undefined ){}
If (otest! = NULL ){}
If (otest! = False ){}
It is equivalent:
If (! Otest ){}

 

2. Reverse Loop
For (VAR I = 0; I <avalues. length; I ++ ){}
After replacement
For (VAR I = avalues. Length-1; I> = 0; I --){}
Reversing loops helps reduceAlgorithmComplexity. It uses a constant (0) as a loop control statement to reduce execution time.

3. Flip Loop
VaR I = 0;
While (I <avalues. Length ){
I ++;
}
After Optimization
VaR I = avalues. Length-1;
Do {
...
} While (-- I> = 0)

 

4. Expand the loop
VaR avalues = [, 7,...];
VaR isum = 0;
For (VAR I = 0; I <avalues. length; I ++ ){
Isum + = avalues [I];
}
After Optimization
VaR avalues = [, 7,...];
VaR isum = 0;
For (VAR I = 0; I <avalues. length; I ++ ){
Isum + = avalues [I ++];
Isum + = avalues [I ++];
Isum + = avalues [I ++];
Isum + = avalues [I ++];
Isum + = avalues [I ++];
}