#14 JS: create a calculator by prompt()

2021 iThome 鐵人賽

DAY 14

Modern Web

Learn & Play JavaScript -- Entry-Level Front-End Web Development系列第 14 篇

13th鐵人賽 front-end frontend javascript js

Vida Lin

2021-09-14 09:23:38

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Final Calculator Design

<!DOCTYPE html>
<html>
<head>
<title>JavaScript</title>
<script type="text/javascript">

var n1=prompt("Please key in a random number.","e.g.123"); 
var n2=prompt("Please key in a random number.","e.g.123");
var result=n1*n2;
alert(result);

</script>
</head>
</html>

Design a Calculator

prompt() is a dialogue box that user can key in values, and it will close until the user submit or cancel.

Basing on the rule, we can separate the user behavior into steps, like:
input: prompt(default value or an example) → operate → output: alert(data)

For example, to create a simple calculator...

var n1=prompt("Please key in a random number." , "7");

var n2=prompt("Please key in a random number." , "7");

var result=n1*n2;
alert(result);

=> The result is 49.

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