Conditional statements
if (condition) {
Code execution if the condition is true
}
Example:
There are a = 1;
if (a < 3) {
document.write('hell word!');
}
if (condition) {
Code execution if the condition is true
}else{
When the code is executed if the condition is false
}
Example:
There are a = 1;
if (a < 3) {
document.write('hello');
}else{
document.write('word');
}
The results: hello
if (condition 1) {
Condition 1 block of code is true
} Else if (condition 2) {
Condition 2 is true execution code block
}else{
Conditions 1 and 2 are not simultaneously satisfied during execution of the code block
}
Example:
There are a = 87;
if (a >= 90) {
document.write ( 'excellent');
}else if(a>60 && a<90){
document.write('良好');
}else{
document.write ( 'fail');
}
Results: Good
switch statement
grammar
switch (expression) {
case n:
Block
break;
case n:
Block
break;
default:
The default block
}
Example 1:
switch (2){
case 1:
document.write('aa');
break;
case 2:
document.write('bb');
break;
case 4:
document.write('dd');
break;
default:
document.write('ff');
}
The output is: bb
Example 2:
switch (true){
case 1:
document.write('aa');
break;
case 2:
document.write('bb');
break;
case true:
document.write('dd');
break;
}
The result is: dd
By Examples 1 and 2 can be found, it can not only output a digital input Boolean may also be described that the data transmission switch
Example 3:
i=14;
switch(i){
case 1:
document.write('a');
case 2:
document.write('b');
default:
document.write('e');
case 3:
document.write('c');
break;
case 4:
document.write('d');
}
The results: ec
break; it will jump out of the switch code.
The last code block Case, here will naturally block the end, it does not require additional break ;.
Default default can not be placed in the last case.