Search Results for: javascript object

This article will show you how to use the JavaScript forEach() method to loop over an array. Pretty much any application of any complexity will require the looping over arrays (lists) of data. The JavaScript forEach() method, which is built into JavaScript array variables, does just this. You’ll be using it a lot – so thankfully, it’s pretty darn easy to use. JavaScript forEach() Syntax arr.forEach(callback(currentValue[, index[, array]]) { // execute something }[, thisArg]); Note that: arr is an array or a variable containing an array callback is the … Read more

This article will discuss the differences between typescript and JavaScript, the problems they solve, and which is best to use. I really like TypeScript, and I use it a lot. It solves so many of JavaScript’s problems and makes writing good JavaScript code much easier (once you’ve learned to use TypeScript). So, this article is more about why you should use TypeScript (when you can use it), when/where you can use it, and the problems it solves. This article goes well with the following articles, giving you an … Read more

The JavaScript eval() function executes a string as JavaScript. This is a massive security risk as, if used in production, it can allow third parties to execute their own code in your app. eval() Syntax eval(string) Note that: string is a string that contains JavaScript Code eval() will return the value returned by executing the code in the string Just don’t use it Example of Javascript eval() This article gets one example only so you can see how eval() works, so that if you accidentally fall on your keyboard and the … Read more

Being able to concatenate (join) two or more strings together is pretty useful – you may be combining user input for storage in a single database column or doing the reverse – combining data from multiple database columns into a single string for display or output. There are several ways to concatenate strings in Javascript, and we’ll cover these methods below, along with some useful examples. The string.concat() Method The string.concat() method will join any number of strings to a given initial string. Syntax string.concat(string1, string2, string3…) Note that: string is … Read more

Here’s a guide on checking whether a string contains another string in the JavaScript programming language using the includes() method. includes() Syntax string.includes(search, start) Note that: string should be a string value or variable search should be the string you are checking for start is the index (position) you want to start searching at. It’s optional Indexes start counting at 0 – The first character of the string is at index 0 returns bool Examples var string = “Linux all over the world”; var result = string.includes(“over”); // Will … Read more

We have covered removing items from arrays in JavaScript, as well as checking whether an item is present in an array. This article will look at copying or returning a subsection of arrays using the slice() method in Javascript. slice() Syntax arr.slice([start[, end]]) Where: arr is an array or existing array variable start is the index to start the slice at If it is undefined, it will default to 0 The index is the position of the item within the array. Remember, they start at 0! end is the index to end the slice at If it … Read more

Want to make a string all lower case in JavaScript? It’s the toLowerCase() method to the rescue! The toLowerCase() method is part of the string object and has full support in all browsers. In JavaScript, strings can either be a primitive or an object – primitives are the most basic kinds of variables, which are not objects, have no methods, and simply represent the given characters. However, String objects have useful methods for manipulating and measuring the string – like toLowerCase(). By default, JavaScript’s string variables are initialized as primitives – but will be automatically … Read more

In this guide, we explain how to measure the length of a string in JavaScript using the length method. JavaScript is a flexible programming language that runs just about everywhere. You can run JavaScript apps in web browsers, build command-line apps you can run in the terminal, mobile apps can be built using platforms like Cordova, and server processes can be written on platforms like Node.js. Naturally, Linux is the environment of choice for many JavaScript developers and is perfect for learning tools like Node.js … Read more

This tutorial will show you how to check whether an array contains a specific value in Javascript, with full examples. JavaScript is a flexible programming language that runs just about everywhere. You can run JavaScript apps in web browsers, build command-line apps you can run in the terminal, mobile apps can be built using platforms like Cordova, and server processes can be written on platforms like Node.js. Naturally, Linux is the environment of choice for many JavaScript developers and is perfect for learning tools like … Read more