Javascript basic tutorial flow control statement

What are the conditional statements?

if statement

if (condition){

Execution code;

}

Example:

Note: x is equal to 5. Execute the if statement. If x is less than 4, execute the following statement. In this code, x does not meet the conditions, so it will not Execute the following statement, the output is empty;

if...else

if (condition){

Execution code if the condition is met

}else{

Execution code if the condition is not met

}

Example:

Note: x =5 Determine whether the condition meets x<4 If the condition is true, execute alert('true'); Otherwise, execute alert('false');

if.... .else if....else

if(condition 1){

Execute statement 1

}else if(condition 2){

Execution statement 2

}else if(condition 3){

Execution statement 3

}else{

Does not meet the above Conditional execution statement 4

}

Example:

switch statement

##switch (condition) {

case 1:Execute statement;break;

case 2:Execute statement;break;

case 3:Execute statement;break;

default :Execution statement;

}

Example:

Note: switch is used in combination with break. When myweek is equal to 1, if there is no break after the execution statement ; Will output all the cases from case 1 to default, plus break. When the conditions are found to be met, no further execution will occur. The switch must have an initial value. When all conditions are not met, the default statement will be executed