How can I deep freeze an object in JavaScript?
Learn how mutability works in JavaScript, its applications to objects and how you can properly freeze them to make them constant.
Code Articles
30 seconds of code contains a curated collection of code articles covering a wide range of development needs. The collection spans many topics, ranging from simple coding problems to theoretical concepts and development techniques.
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JavaScript · How can I detect the device type with JavaScript?
Learn how to detect whether a page is being viewed on a mobile device or a desktop.
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JavaScript · Pluralize a JavaScript string
Learn how to pluralize a string in JavaScript based on a number.
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JavaScript · Check if the bottom of the page is visible using JavaScript
If you've ever needed to check if the bottom of the page is visible, this article will help you do just that.
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JavaScript · Use JavaScript to find all the images in an element
Use simple DOM queries to find all the images contained within an element.
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JavaScript · Get colon time from a JavaScript date
Get the time part of a Date object in the format HH:MM:SS.
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JavaScript · Escape a regular expression in JavaScript
Learn how to escape a string to use in a regular expression.
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JavaScript · Copy sign from one number to another in JavaScript
Copy the sign of one number to another without changing its absolute value.
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JavaScript · Using a Proxy to implement the Observable pattern
Use the Proxy object to implement the Observable pattern in JavaScript.
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JavaScript · Check if a year is a leap year in JavaScript
Having a hard time wrapping your head around the math involved in checking for leap years? You might not need to!
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JavaScript · Can I check if a JavaScript string contains a substring, regardless of case?
Search for substrings in JavaScript strings without worrying about case sensitivity.
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JavaScript · Normalize line endings in a JavaScript string
Having trouble with inconsistent line endings in your strings? Normalize them with this handy JavaScript function!
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JavaScript · Toggle fullscreen mode for an element using JavaScript
Did you know you can use JavaScript to toggle fullscreen mode for an element on a webpage? Let's learn how!
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JavaScript · Command-line arguments in Node.js
Learn how to extract command-line arguments passed to a Node.js script.
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JavaScript · Weekday name from a JavaScript Date object
Get the name of the weekday from a JavaScript
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JavaScript · Read a file and return an array of lines
Parse a text file and return an array of lines, synchronously or asynchronously, using Node.js.
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JavaScript · Indent a JavaScript string
Indent each line in a string by a specified number of spaces or a custom indentation character.
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JavaScript · Remove non ASCII characters from a JavaScript string
Remove non-printable ASCII characters from a string in JavaScript.
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JavaScript · What are the differences between var, let and const in JavaScript?
JavaScript variables can be declared a handful of ways. However, understanding their differences can drastically change the way you code.
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JavaScript · Validate a number in JavaScript
Check if a value can be safely converted to a number in JavaScript.
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JavaScript · Calculate the angle between two vectors in JavaScript
Learn how to calculate the angle (theta) between two vectors in JavaScript.
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JavaScript · Midpoint of two points
Calculate the midpoint between two pairs of points in a 2D plane, and beyond.
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JavaScript · Count the occurrences of a value in a JavaScript array or string
Given a value, find out how many times it appears in an array or string.
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JavaScript · Can I reload a module in Node.js?
Ever wanted to reload a module in Node.js? Here's how you can do it.