JavaScript statement semantics Daquan (2)

1. Arithmetic related

+,-,*,/,%

The subtraction and the remainder, respectively.

2.math.pow (A, B)

A's B-square

3.toFixed (a)

Rounds a number to a specified number of decimal digits

4. k++;

++k

It looks the same, but there are some tiny differences in the operation.

var k=0

Alert (k++)

Alert (++K)

Of the two equations above, the result of the first one is 0, the second one is 1.

For example: alert (++k + k++ + ++k + k);

In the formula, the first execution ++k, this time K is +1 at the same time, ++k immediately effective, so the formula becomes: Alert (1 + k++ + ++k + K); K=1

Immediately thereafter, the execution k++,k is 1, but the k++ value remains 1, so the result is: alert (1 + 1 + ++k + k); k=2

Then ++k executes, K becomes 3--alert (1+ 1 + 3 + k); k=3

Finally executes +k, becomes alert (1+1+3+3); k=3

Result is 8

5. IsNaN (v)

Whether it is a number

6.

switch (i) {
Case 0:

CASE1:

Alert ("AAA");

Break

A conditional statement that executes the corresponding statement when the value of I and the following case value are the same. Note that there is a word: break, which means that if you do not jump out, then after you execute sentence A, the program will continue to execute a+1,a+2 until a jump statement exists.

7.

var _name = "Background";
_div.style[_name] = _value;//_name refers to a variable, which refers to the string "background"
_div.style._name = _value;//_name is not a property of style, so it cannot be found

8.

ToString (2)//decimal to Binary

parseint (10, 2)//10 is represented by a binary and returns its decimal

JavaScript statement semantics Daquan (2)