## Submodule 7.2: Loops

• for loop
• while loop

### while loop

We use while loops when we don’t know how many times we want it to run.

The while loop has the following syntax:

while (condition) { code block to be executed}

The while loop, loops through a block of code as long as a specified condition is true.

##### Example 1
/* add consectuive integers until we get to 100*/var i = 0, sum = 0;while(sum <= 100){    /*here we increment i, then add it to sum*/    i = i + 1;     sum = sum + i;}/*the loop exits when sum reaches or exceeds 100*/console.log("We added up to "+i+" to get to 100");

This example uses a while loop to add consecutive integers until the sum equals or exceeds 100. The while condition tests if this is true, and at each loop it increments i and adds it to sum. The while loop works well here since we don't know how many times the loop will have to run.

Tip: Copy the above piece of code and paste it directly into the console, to see how it works.

In this spreadsheet, you can see the values of the variables

var j = 0;var sum = 0;while (sum < 1000) {  j = j + 1;  if (j % 2 == 1){       sum = sum + j;  };};console.log(j)