Java Operators and Control statements

1. Operators:
1.1 + (addition, positive number, connector)
True is 1. False is 0

　　

var a = 1;document.write ((1+true) + "<br/>");d Ocument.write ((1+false) + "<br/>");d ocument.write ("Hello" + 1); Hello1

1.2/Division

Because JS has only number type, so two integers can not be integers when the result is a decimal

var a = ten;    var b = 3;    document.write ("Division operation is:" + (A/b) + "<br/>"); If two integers are not integers, the result is a decimal.

1.3 Comparison operators

The rules for comparing strings to strings are:
Case 1: You can find different characters in the corresponding position, then compare the size of the first different character.
Case 2: Cannot find the different characters on the corresponding position, this time compares the length of two strings.

Note: When a string is compared to a number, the string is converted to a number before being compared

document.write ("10 greater than 3?") "+ (10>3) +"<br/>");    document.write ("10 String greater than 3 string?") "+ (" > ") +"<br/>"); String compared to string    document.write ("10 is greater than string 9?"). "+ (> 9") + "<br/>"); /* strings can also be compared to numbers. When a number is compared to a  string, the string is converted to a number before being compared.

1.4 Logical operators

Only && | |

1.5 Three mesh operator

Boolean expression? value 1: Value 2;

2. Control process

2.1if statements

Format:

if (judging condition) {
Code that meets conditional execution
}

The special point of the IF statement:
1. The If statement condition in JavaScript can not only write Boolean expressions, but also write any data.
Number not 0 is true and 0 is false.
String content cannot be NULL is true, the content is false when empty.
Undefined:false (but must first be defined beforehand)
Nan:false

2.2 SELECT statement:

Switch statement
Switch (variable) {
Case value 1:
Break
Case Value 2:
Break
Case Value 3:
Break
.....
Default
Break
}

The Special place:
1. In JavaScript, a case can be followed by a constant and a variable can also be followed by an expression.
　　

    var option = "A";        var a = "a";    VAR score =98;    Switch (option) {case        score>=90? " A ":" B ":            document.write (" Java ");            break;        Case "B":            document.write ("PS");                Case "C":            document.write ("JavaScript");            break;        Case "D":            document.write ("C + +");            break;    }

　　

Java Operators and Control statements