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in javascript how would I create an empty array of a given size
Psuedo code:
X = 3;
createarray(myarray, X, "");
output:
myarray = ["","",""]
209
One common way of creating an Array with a given length, is to use the Array constructor: const LEN = 3; const arr = new Array(LEN); assert. equal(arr. length, LEN); // arr only has holes in it assert.
The first way is that you can get an empty array by assigning the array literal notation to a variable as follows: let firstArr = []; let secondArr = ["Nathan", "Jack"]; The square brackets symbol [] is a symbol that starts and ends an array data type, so you can use it to assign an empty array.
To create an empty array of a specific length, let's say 5 , we will pass null as the first argument, and the second is the array Array(5) . This will create an array of length 5 and initialize each element with an undefined value. Alternatively, you can also do the following.
1) Assigning it to a new empty array This is the fastest way to empty an array: a = []; This code assigned the array a to a new empty array. It works perfectly if you do not have any references to the original array.
1) To create new array which, you cannot iterate over, you can use array constructor:
Array(100) or new Array(100)
2) You can create new array, which can be iterated over like below:
a) All JavaScript versions
Array.apply(null, Array(100))
b) From ES6 JavaScript version
[...Array(100)]
Array(100).fill(undefined)
Array.from({ length: 100 })
You can map over these arrays like below.
Array(4).fill(null).map((u, i) => i) [0, 1, 2, 3]
[...Array(4)].map((u, i) => i) [0, 1, 2, 3]
Array.apply(null, Array(4)).map((u, i) => i) [0, 1, 2, 3]
Array.from({ length: 4 }).map((u, i) => i) [0, 1, 2, 3]
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var arr = new Array(5);
console.log(arr.length) // 5
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