Archive results for: JavaScript Tips

JavaScript Tip: Nested Arrays

Sometimes, you’ll need to store an array within an array. Sometimes, you’ll require even more nesting.

Note: although it’s possible to nest a number of arrays, I’d advise against it, as working with many array indices can be confusing to work with.

Let’s start with two simple arrays, which we’ll call them x and y. We’ll fill x with some values:

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JavaScript Tip: Reading from an Object

Reading a value from an object can also be accomplished using bracket or dot notation:

Unlike arrays, it’s not possible to read the contents of an object using a numeric index. The only type of index that can be used is a named one:

JavaScript Tip: this and Objects

When a function is created, a keyword called this is created (behind the scenes), which links to the object in which the function operates. Said another way, this is available to the scope of its function, yet is a reference to the object of which that function is a property/method. So every function, while executing has a reference to its current execution context.

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JavaScript Tip: Iterating over an Object

Iterating over an object isn’t as simple as looping over an array. With an array, you simply increment an index value and use that to step through the array. With objects, there is no index value.

Objects are collections of key/value pairs, so you need to step through them differently:

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JavaScript Tip: Adding Property to an Object

After you’ve declared your object, however, you can still add key/value pairs to it in a couple of ways.

This is known as bracket notation. The alternative and more common syntax is dot notation. Here’s an example:

Dot notation is simpler than bracket notation; however, there are certain tasks that can only be done with bracket notation. For example, you can use a variable inside the brackets, which can’t be done using dot notation. Bracket notation also supports strings containing spaces and other characters that are invalid in dot notation.

JavaScript Tip: Creating an Object

As with arrays, there are a couple of ways to create objects, and, just like arrays, one is preferred over the other. So even though you can do this:

You can also use object literal notation:

It’s safer to use the object literal notation {} as it’s unable to be overwritten. The object literal represents a new, empty object. Read more ›

JavaScript Tip: Strict Equal (===)

A strict equal comparison performs no conversion of types. Where “” == 0 would return true for a regular equal comparison, “” === 0 would not, since an empty string does not equal zero:

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