Some useful techniques for array operation using javascript
There are few development tips for Javascript array operation, these tips will reduce your development time.
1. Initialize an array with default value
If you are working with fixed length of array and you need to initialize it with fixed value. We have traditional way of initialzation but also we have alterative and it is a shortcut method.
Initialize one dimensional array If you want to intialize one dimensional array of specified length and apply the default values.
const oneArray = Array(6).fill('xxx');
//["xxx", "xxx", "xxx", "xxx", "xxx", "xxx"]
Initialize Multi-dimentsional array
If you want to intialize multi-dimensional array of specified length and apply the default values.
const multiArray = Array(6).fill(0).map(() => Array(5).fill('xxx'));
// [["xxx", "xxx", "xxx", "xxx", "xxx"], ["xxx", "xxx", "xxx", "xxx", "xxx"], ["xxx", "xxx", "xxx", "xxx", "xxx"], ["xxx", "xxx", "xxx", "xxx", "xxx"], ["xxx", "xxx", "xxx", "xxx", "xxx"], ["xxx", "xxx", "xxx", "xxx", "xxx"]]
2. Find Sum, Maximum and Minimum of an array.
It is a very tricky and this is a common question in most of interviews. To solve this we can use javascript standard function "reduce()".
The reduce() method executes a reducer function for array element.
const sampleArray = [51,14,17,28,39,32];
Sum
sampleArray.reduce((a,b) => a+b);
//Result: 181
Finding Maximum
sampleArray.reduce((a,b) => a > b ? a : b); Math.max(...sampleArray)
//Result: 51
Finding Minimum
sampleArray.reduce((a,b) => a < b ? a : b); Math.min(...sampleArray)
//Result: 14
3. Empty an array
If you want to clear the values in the array variable then set the length equal to Zero.
let array = ["J", "A", "V", "A", "S", "C", "R", "I", "P", "T"]
array.length = 0
console.log(array) // []
4. Split the word into an Array
We can split the word by given identifier, this is can be achieved by using split()
Eg :- 1
let array = "JAVASCRIPT"
console.log(array.split(""))
Result //["J", "A", "V", "A", "S", "C", "R", "I", "P", "T"]
Eg :- 2
let array = "JAVA-SCRIPT"
console.log(array.split("-"))
Result //["JAVA", "SCRIPT"]
the above are the two example of split function on different scenario.
5. Combine two or more arrays
If you want to Merge or Combine two or more arrays then use the Spread Operator or Concat()
using Spread or Extension operator
const start = [1, 2]
const end = [5, 6, 7]
const result = [9, ...start, ...end, 8] // [9, 1, 2, 5, 6, 7 , 8]
using concat method
const start = [1, 2, 3, 4]
const end = [5, 6, 7]
start.concat(end); // [1, 2, 3, 4, 5, 6, 7]
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