while

Summary

Executes a statement or series of statements while a specified condition is true.

while ( expression ) {
  statements
}

expression: Required. A Boolean expression that is checked before each iteration of the loop. If expression is true, the loop is executed. If expression is false, the loop is terminated.
statements: Optional. One or more statements to be executed if expression is true.

var i = 0;

while (i < 5) {
  console.log("This runs 5 times");
  i++;
}

var i = 0;

while (i < 100) {
  if (i == 5) {
    // Stop the while loop early
    break;
  }
  console.log("This happens 5 times");
  i++;
}

 The while statement checks the expression before a loop is first executed. If expression is false at this time, the loop is never executed.

The while statement keeps iterating until the conditional expression returns false, or encounters a break statement.

It’s essential that the expression can become false or that that loop is terminated with the break statement to prevent an infinite loop.