JavaScript while statement

Examples

In this case the loop will continue to run as long as the variable i is less than 5 ::

var text = "";
var i = 0;
while (i <5) {
text + = " The number is" + i;
i ++;
}

text output is:

The number is 0
The number is 1
The number is 2
The number is 3
The number is 4

try it"

Bottom of this article contains more examples.

Definition and Usage

while as long as the statement specified condition is true, it will execute a loop.

As long as a specified condition is true, the loop can always execute the code. .

JavaScript support different types of loops:

for - a certain number of cycles code block
for / in - loop through the properties of an object
while - when a specified condition is true cycle specified block of code
do / the while - the same as the specified condition is true cycle specified code blocks, but the statement will be executed once before the conditional

Tip: Use the break statement to jump out of circulation, the use of continue statement to jump out of the current iteration, and start the next iteration.

Browser Support

Statements
while	Yes	Yes	Yes	Yes	Yes

grammar

while (condition) {
code block to be executed
}

Parameter Value

parameter	description
condition	have to. Define the execution condition for the loop. If true, the loop will continue, if it returns false, the cycle stops. Note: If your condition has been true, the cycle never ends. This may cause the browser to crash. NOTE: If you forget to add conditions to the value of the variables used in the cycle never ends. This may cause the browser to crash.

technical details

JavaScript version:	1.0

More examples

Examples

Cycle through the index of the array, the output car name:

var cars = [ "BMW", "Volvo", "Saab", "Ford"];
var text = "";
var i = 0;
while (i <cars.length) {
text + = cars [i] + " ";
i ++;
}

try it"

Analysis examples:

Implementation, we set the variable before the start of the cycle (var i = 0;)
Then, we define what the condition of the loop. Know the variable i is less than the length of the array (4)
Each time through the loop, the variable is incremented 1 (i ++)
Once the variables are no longer less than (array length), on the condition is false, the loop is terminated.