Yet, the creators of RxJs chose to increase complexity by adding an extra method. It seems pointless birli such, so I'm suspecting there's more to it than what meets the eye.

If the list you're provided already özgü elements in it, those will be kept, and the new ones will be added to those. It also returns the destination list for convenience.

The RxJS operator map emanet be used to map the stream value to a new value. However, if you want to map to website a static value that does hamiş depend on the stream value, you gönül use the mapTo operator. This operator accepts the value directly and you don't need to create an additional function.

As you kişi see, the map method is extremely flexible with a wide variety of use cases, but how does this translate to map with RxJS, and when would you put this to use with observables?

Lastly, there may also be times where you always want to map to a single value, no matter the input. For these situations, you sevimli use the mapTo operator.

bey you emanet see, irrespective of whatever value emitted, it always transformed to 4. Now you might be thinking, we can use mapTo operator for our above example of getting input value on button click. Let’s check.

Now from arrayOfStudent, we want all the name of students in capital letters, so apply map like this:

I'm reading the docs for mapTo and I'm simply not getting the point of that operator's existence. I get what it does but the two line below should produce equivalent result.

map operator is used when we want to transform a stream into a value which is not related to the emitted stream.

RxJS mapTo() operator is a transformation operator that emits a constant value kakım an output along with the Observable whenever the source Observable emits a value.

The pluck operator accepts a list of values which describe the property you wish to grab from the emitted item. For instance, using our event code example from above we could use pluck instead of map to extract the code property from the event object:

We can confirm this in the RxJS source code by seeing the function we provide is invoked, with the result being passed on to the subscriber (destination):

If you have spent time working with JavaScript arrays you may already be familiar with Array.map. When dealing with arrays, the map method lets you transform an array by applying a provided function (often referred to kakım a 'projection' function) to each item within the array. For instance, let's say we have an array of numbers 1-5:

The submit event is ignored and value of the input box is sent birli transformed value of the submit event. That is requirement too, we need to capture the username when submit button is clicked.