Map array in array javascript
Before we dive into the Show
The The
The function will look over the array of people and will run once for each item in the array. It therefore makes more sense to name the first argument person, the singular version of people. Most of the time you will only need and use the first argument.
We can use an arrow function instead of an anonymous function. And as we only are using one argument we can remove the brackets from person.
Inside the function we need to return something. As the
We can return anything we want even though the original array is an array of Objects we could return a string instead. If we return a string with some text then we will get that same string for each item in the array.
Normally what we want to do is to modify the data or add to it. We could create a variable called fullName and concatenate the values of firstName and lastName.
This will give us a new array with only the fullName returned as that is all we asked for. If however we wanted to have the full name as well as all the rest of the contents in the array we can also easily return them.
In this example we only have 2 other keys the firstName
and lastName but imagine if we had more such as age, address etc. It would be tedious to have to write all of these out. Instead we can use the spread operator. The spread operator expands an iterable object into the list of arguments. We prefix the value with an ellipsis of three dots
And that's it. We now have a new array of names with a fullName plus the first and last names. We can add more keys to the objects in our
people array and we will receive these new keys without having to modify anything thanks to the use of the spread operator. And of course we could in fact add more than one item to the names array if we wanted to. Have fun with Feel free to play around with the codepen I created. Learn more
How do you map an array within an array?map method gets called with each element in the array and the index of the current iteration.. Use the map() method to iterate over the outer array.. On each iteration, call the map() method on the nested array.. Render the elements of the nested array.. How do I map an array in JavaScript?The syntax for the map() method is as follows: arr. map(function(element, index, array){ }, this); The callback function() is called on each array element, and the map() method always passes the current element , the index of the current element, and the whole array object to it.
Can we use map on array?map() creates a new array from calling a function for every array element. map() calls a function once for each element in an array. map() does not execute the function for empty elements. map() does not change the original array.
Does array map return a new array?Return Value: It returns a new array and elements of arrays are result of callback function. Below examples illustrate the use of array map() method in JavaScript: Example 1: This example use array map() method and return the square of array element.
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