JS Summary loop exit loop function

While loop

while (condition) {code to execute if condition is set}

* The general condition variable needs to increment, otherwise it will enter the dead loop (infinite loop), the browser crashes or even the computer freezes.

For example, a row-by-line output of 1-100 digits

var i = 1;

while (i<=100) {

document.write (i+ "<br/>");

i++;

}

Do...while Cycle

do{Execute code}while (conditions, if the condition is true, continue the loop, otherwise abort the loop)

For example, a row-by-line output of 1-100 digits

var i = 1;

bo=

document.write (i+ "<br/>");

i++;

}

while (i<=100)

* Unlike while: Do...while is the first to execute code before judging the condition, while the while opposite

For loop

For (initial value of parameter; parameter condition; parameter increment) {Condition for execution code}

Where the parameter is a local variable

For example, a row-by-line output of 1-100 digits

for (Var i=1;i<=100;i++) {

document.write (i+ "<br/>");

}

* It is recommended to use a for loop to facilitate program reading

Terminate loop: break,continue

Break: Exit the entire loop now

Continue: Skipping execution code for the current loop to continue looping

For example:

for (Var i=1;i<10;i++) {

if (i==5) {break}

}

alert (i); Output is 5

for (Var i=1;i<10;i++) {

if (i==5) {continue}

alert (i);

}

Output of 1,2,3,4,6,7,8,9 will find alert (5) skipped

Function

JS has a number of functions, including built-in functions and custom functions.

Built-in functions: in fact, we often use the alert (parameter) can also be seen as a function, it represents the way to pop a window, and the window prompt is the function of the parameter

Custom functions: We can create a function with a specific function method, for example, we create a function area (s,h)//where S is the bottom, H is high

To create a custom function:

Functions Area (s,h) {}//area is a custom function name, S,h is a custom parameter

To add functionality to a function:

function Area (s,h) {

var area=s*h*0.5;

return area;

}

In this way, the area of a triangle with a height of 5 is 10, as long as the function is directly called to write the functions can be: areas (5,10);

JS Summary loop exit loop function