What does the JavaScript syntax foo: mean?

Question

what does the following code meaning? (it is not json - it is code which does not generate error by js interpreter)

foo: 5

The reason for t

Answer 1

It's a JavaScript label: documentation here.

You can use a label to identify a loop, and then use the break or continue statements to indicate whether a program should interrupt the loop or continue its execution.

Note that JavaScript has NO goto statement, you can only use labels with break or continue.

Example usage (from MDN)

var itemsPassed = 0;
var i, j;

top:
for (i = 0; i < items.length; i++){
  for (j = 0; j < tests.length; j++) {
    if (!tests[j].pass(items[i])) {
      continue top;
    }
  }

  itemsPassed++;
}