What is the difference between x-- and --x

The difference between x-- and --x: 1. [--x] decrements the value of x by 1 first, and then calculates the value of x; 2. [x--] calculates x first value, and then decrement the value of x by 1.

##The difference between x-- and --x:

• - -x means that the value of x is decremented by 1 first, and then the value of x is calculated.

• x-- is to first calculate the value of x, and then decrement the value of x by 1.

Example 1:

var x = 10;
console.log(x--);
console.log(x);

Output:

10
9

The first output is 10, x--first use the value of x in the current expression , and then decrement the value of x by 1; the second output is 9, because x has decremented by 1 after the previous instruction.

Example 2:

var x = 10;
console.log(--x);
console.log(x);

Output:

9
9

The first output is 9, --x first decrements the value of x by 1, and then in the current expression Use the value of x; the second one also outputs 9, and x has been decremented by 1 after the previous instruction.

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