FAQ: Variables - The Increment and Decrement Operator

This community-built FAQ covers the “The Increment and Decrement Operator” exercise from the lesson "Variables ".

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This exercise can be found in the following Codecademy content:

Web Development

Introduction To JavaScript

FAQs on the exercise The Increment and Decrement Operator

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Why would you write out new code to put the number up 1 or down 1.
Rather than simply change the number of the original variable?

what if you don’t know the value because its user input? Or you have a counter on your website, then increasing the counter by one is easier when you have a visitor

or when you use a for loop?


The use of +=, ++ and other daft contractions was introduced in ‘C’ by Kernighan and Ritchie because the original ‘C’ compilers were hosted on PDP8 minicomputers. The available memory was minimal
and the quality of the code development tools even more minimal. Variable names at one point were limited to five characters! It made some sort of sense then to use as few characters as possible. But it also made the code almost unreadable which from a code maintenance point of view is not a good thing. If you really want to see code contraction gone mad read PJ Plaugers’ ‘C’ library text. I have
been writing ‘C’ and various assembly codes for real-time embedded development since 1988. Just as
soon as it became reasonable to do so I threw out the contractions in favour of a more flowing style
of code writing. I just started looking at JavaScript as an additional tool in the GUI/test arsenal and
am really surprised the archaic way of writing formulae has made it into the specification of a
supposedly modern(-ish) web-based language.

1 Like

You should either add


to the existing code so we can see the changes, or promt us to write it ourselves in a third point in the execise.
Otherwise people who dont think of it will not see the output


why does console.log(variable++) not make changes to the variable the same way variable++ does?

it does:

i = 0;

see? i has increased. I would recommend reading:


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Good catch @beta5196194865
variable++ increments the original value by one and then evaluates to the value before it was incremented.

const messages = ['zero','one','two'];
let i = 0;
console.log(messages[i++]);   // zero
console.log(i);               // 1
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