Colon Within A Javascript Function While Loop

I was poking around some HTML5 Javascript demos and came across something I've never seen before in the syntax. Take a look at the run function and notice how the search object not

Solution 1:

This is not object (literal) notation, it is defining a label.

A label can be used to give a looping construct a name. The benefits of doing this is that you can create more powerful breaks; or continues; by referencing outer loops (by their labels).

Note that how the structure of the program you referenced is a:

search: while () {
   for (;;;) {

   }
}

... and the author is using continue search;inside the for loop to continue the execution of the while loop.

As for what's happening on line 18, if (n % i == 0) is using the modulo (%) operator to get the remainder between dividing n / i, and checking whether it's 0.

Solution 2:

search: is a label in this case that you can use to refer to this loop.

For example you can break this loop by doing break search;

Solution 3:

Since no one answered both your questions.

search: while, here search is a label which helps uniquely identify the while loop, which as mentioned, helps when using break and/or continue within nested loops.

Line 18 (n % i ===0)

Is basically looking for an odd number by applying the modulo operator.

Solution 4:

This is a label, mainly used in nested loops to break/continue a certain loop that is marked by this label. This is a standard in every programming language and not javascript specific. Read more here in section "Using Labels to Control the Flow"

http://www.tutorialspoint.com/javascript/javascript_loop_control.htm