For loops can be used to repeatedly execute some code. In the following example, a variable called x is created and the number 1 is added to it 10 times.
var x = 0;// creating a new variable, with an initial value of 0
for (var i = 0; i <10; i++)
x = x + 1;
The next example, does exactly the same thing as the the previous example, except that the number of loops (i.e., iterations) is itself set in a different variable.
var n_iterations = 10;
var x = 0;
for (var i = 0; i <n_iterations ; i++)
x = x + 1;
This does exactly the same thing as the previous example, except that 1 is added in a slightly more efficient way:
var n_iterations = 10;
var x = 0;
for (var i = 0; i <n_iterations ; i++)
x += 1;
This does exactly the same thing as the previous example, except that 1 is added automatically each time by using ++.
var n_iterations = 10;
var x = 0;
for (var i = 0; i <n_iterations ; i++)
x++;
When we wish to execute multiple lines of code within each branch, this is done using parentheses. In this example, 1 is added to x and then it is doubled and this occurs 10 times.
var n_iterations = 10;
var x = 0;
for (var i = 0; i <n_iterations ; i++){
x++;
x *= 2;
}
See also
Next
If and else if JavaScript Statements
JavaScript Mathematical Functions