Explore the use of self increasing and self decreasing operators

1. introduction

Increment operator （ ++ ） And decrement operators （ – ）
To distinguish x++ and ++x So I write this article .

2. use JavaScript Code implementation

Self increasing operation

    // Self increasing , Self increase means adding 1 Figures obtained 
    var x = 5;
    x++;//x++ Equate to x = x + 1;
    console.log(x);// The result is 6


    // X++  And  ++x There are two uses 
    var a1 =5 , a2 = 5 ;
    var b;
    var c;
    b=a1++;
    c=++a2;
    console.log(b);// Output 5
    console.log(c);// Output 6
    console.log(a1);// Output 6
    console.log(a2);// Output 6

Through the above code, we can find , Variable value is 5, No matter through Variable ++ still ++ Variable , The values of variables are added by themselves 1, But there are differences when assigning values to other variables in the process of self addition .
In fact, we don't need to know the underlying principle of the code , There is a rule to remember , Who is close to the right of the equal sign , Just use who .
for example ,
s = x++ To the right of this equal sign is the variable , Then assign a value to the variable first ;（ First use then add ）
s = ++x To the right of this equal sign is a plus sign , Then calculate self addition first , Get the result and assign value ;（ Add first and then use ）
The same is true of self subtraction

	var x1 =9 , x2 = 9 ;
    var y;
    var z;
    y=x1--;
    z=--x2;
    console.log(y);// Output 9
    console.log(z);// Output 8
    console.log(x1);// Output 8
    console.log(x2);// Output 8
    

Who is close to the right of the equal sign , Just use who .
s = x-- To the right of this equal sign is the variable , Then assign a value to the variable first .（ Use first and then subtract ）
s = --x To the right of this equal sign is a minus sign , Then calculate self subtraction first , Get the result and assign value .（ First reduce and then use ）

3. Summary

The overall difference is - - -（ Operation before use ） And - - -（ Use first and then calculate ） The difference between .
Practice and you will be impressed .