CoMo Science

Category: JavaScript

  • addEventListener()

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    The addEventListener() method allows you to add an event to an HTML element in JavaScript. Although the example used often shows this function being used to add a response of a ‘click’ event to a button, there is an easier way by using the ‘onclick’ property. This is the typical way to use a button:…

  • Server-side vs. client-side

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    As you are learning HTML, JavaScript and CSS, you are going to realize that there are things that webpages do, that you can’t do with HTML, JS or CSS. At that point, it is time to understand the server-side vs. client-side of the web. All of the web development you have been doing so far,…

  • Writing more complex code

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    When you first start learning to program, you are often motivated by a desire to create a specific program, like a game. But writing larger programs can be frustrating due to the number of errors and your lack of progress. I discuss how to develop you code step-by-step in order to achieve early success and…

  • If statements

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    In JavaScript, if statements are written like this: This is one of the main ways that we use to get a program to make a decision based on input and do something different than it would otherwise do. When the program reaches the if statement, it will determine if the condition is true or false.…

  • Running a JS function with an HTML button

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    This short tutorial shows how to run a function written in JavaScript when a button is pressed. The Code How the code works The HTML code has three tags: The JavaScript code defines one function, called buttonClick. The function contains a single line of code, which is run when the button is pressed. The function…

  • Troubleshooting your webpage

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    This code troubleshooting guide emphasizes the importance of clear formatting, comments, and variable names. It also highlights common HTML and JavaScript errors to watch out for and suggests using the browser console for error messages and variable value checks. Proper formatting and console usage can greatly facilitate code troubleshooting.

  • setInterval()

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    setInterval is a JavaScript command which takes two parameters. The first is the name of a function and the second is the time interval, in milliseconds, that this function should be repeatedly called. For example: In this code, setInterval calls the function ‘update’ every 10 milliseconds. The function increases the variable i by 1 and…

  • Arrays

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    An array in JavaScript is a variable containing multiple values. Arrays are indexed from 0 to n-1. By using a for loop, you can iterate through the array’s values without needing to list each value individually. Proper formatting makes an array’s structure easier to understand. Arrays are fundamental in JavaScript programming.