What am I missing? .concat() adds a value into a new array, while .unshift() adds one to the front of the same array. I’ve tried function addToFrontOfNew ( arr, element ) { let newArray = arr.unshift(element); return newArray.slice(); } // or function addToFrontOfNew(arr, element) { let new…

Of course, there is also the ES6 solution with a spread operator: let arr = [1, 2, 3] let newArr = [127, ...arr] console.log(arr) // [1, 2, 3] console.log(newArr) // [127, 1, 2, 3]

[image] Array.prototype.unshift() The unshift() method adds one or more elements to the beginning of an array and returns the new length of the array. [image] Array.prototype.concat() The concat() method is used to merge two or more arrays. This method …

Those are two different functions. newArr = arr1.concat(arr2) In this example, a new array is created and assigned to newArr. This is important: arr1 and arr2 are unchanged. But unshift actually changes the array: myArr.unshift(127) myArr is now a different array with the number 127 added to th…

Yes, unshift returns the number of elements in the array: let arr1 = [1, 2, 3] let arr2 = [4, 5, 6] let arr3 = arr1.concat(arr2) console.log(arr1) // [1, 2, 3] console.log(arr2) // [4, 5, 6] console.log(arr3) // [1, 2, 3, 4, 5, 6] let myArr = ['pear', 'orange', 'apple'] let x = myArr.unshift('…

I tried that solution also, I too thought it would work but it only succeeds in creating a new array, but not adding the value to front or work for empty arrays. Thanks for the replies everyone, I’ll post my answer when I figure it out. Here are the instructions (just practice, not classwork) /* W…

Did you want a solution or did you want to figure it out yourself?

You can do this with a spread operator.

Good question haha. I guess I just want to know why these arr.slice().unshift(element); //or let newArray = array.unshift(element); return newArray.slice(); aren’t working, or what I may have missed thats not coming to mind. .concat() will add the value to a new array, is there like a sort met…

For the arr.slice().unshift(7) it will return what unshift returns since it is the right-most operation , not the new array And the second one calls slice on what unshift returns which is not an array (in this case) You’re basically there, just a slight tweak

[image] AliasAJ: arr.slice().unshift(element); Array.slice() returns all numeric properties/indeces between two given integers. This works on Strings or Arrays as they by nature use numeric indeces. Array.unshift() alters the array it is used on. It inherits the context of the array, and a…

Adding a value to the front of a NEW Array?

Programming JavaScript

AliasAJ May 7, 2018, 4:51am 4

Yes I tried .unshift(), it changes the current array but does not create a new array, just adds a value to the beginning of the old one.

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Adding a value to the front of a NEW Array?

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