The final expression is a statement that is executed at the end of each loop.

Now we are saying that the condition is true as long as i is less than 4 in this example. We already established that our iteration variable, i, represents 0 to start. Just as we saw in the while and do.while loops, for loops usually contain a condition. The variable i stands for iteration, is consistent, and keeps the code compact. While the variable can be named anything, i is most frequently used. We’re declaring a variable called i with the let keyword (the keyword var may also be used) and giving it a value of 0. Our first expression is the initialization. Let’s go over each expression in the loop to understand them fully. If we needed to increment through more numbers we would have needed to write even more lines of code. Without the loop in place, the code block is repetitive and consists of more lines. NoLoop.js // Set initial variable to 0 let i = 0 // Manually increment variable by 1 four times Let’s use a basic example to demonstrate what each of these statements does. In the syntax above there are three expressions inside the for statement: the initialization, the condition, and the final expression, also known as incrementation. for ( initialization condition final expression ) Let’s take a look at an example of what that means. The for statement is a type of loop that will use up to three optional expressions to implement the repeated execution of a code block. In this tutorial, we will learn about the for statement, including the for.of and for.in statements, which are essential elements of the JavaScript programming language. Similar in that they are also conditionally based, for statements also include extra features such as a loop counter, allowing you to set the number of iterations of the loop beforehand. The most basic types of loops used in JavaScript are the while and do.while statements, which you can review in “ How To Construct While and Do…While Loops in JavaScript.”īecause while and do.while statements are conditionally based, they execute when a given statement returns as evaluating to true.

Loops are used in programming to automate repetitive tasks.

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