8 Must Know Javascript Array Methods

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Here are the 8 JavaScript Array Methods you should know.

1. filter()

The filter() method returns an array filled with all array elements that satisfies the condition.
If no elements satisfies the condition, it returns an empty array.

      let arr = [1, 2, 3, 4, 5, 6];

      // returning items less than 4
      let filteredArr = arr.filter((item) => item < 4);

      console.log(filteredArr); // output: [1, 2, 3]

2. map()

The map() method returns a new array with the results of calling a function for every array element.
The map() method calls the provided function once for each element in an array, in order.

      let arr = [1, 2, 3, 4, 5, 6];

      // adding one to each array element
      let mappedArr = arr.map((item) => item + 1);

      console.log(mappedArr); // output: [2, 3, 4, 5, 6, 7]

3. find()

The find() method returns the value of the first element in an array that satisfies the condition.
The find() method executes the function once for each element present in the array.

      let arr = [1, 2, 3, 4, 5, 6];

      // finding element greater than 4
      let resultArr = arr.find((item) => item > 4);

      console.log(resultArr); // output: [5]

4. forEach()

The forEach() method calls a function once for each element in an array, in order.

      let arr = [1, 2, 3, 4, 5, 6];

      arr.forEach((item) => {
        console.log(item); // output: 1 2 3 4 5 6
      });

5. some()

The some() method checks if any one of the elements in an array satisfies the condition.
If satisfied, it returns 'true' otherwise 'false'.

      let arr = [1, 2, 3, 4, 5, 6];

      // checking is any array element equals to 3
      let isThree = arr.some((item) => item === 3);

      console.log(isThree); // output: true

      // checking is any array element equals to 10
      let isTen = arr.some((item) => item === 10);

      console.log(isTen); // output: false

6. every()

The every() method checks if all elements in an array satisfies the condition.
If satisfied, it returns 'true' otherwise 'false'.

      let arr = [1, 2, 3, 4, 5, 6];

      // all elements are less than 6
      let lessSix = arr.every((item) => item <= 6);

      console.log(lessSix); // output: true

      // all elements are greater than 10
      let greaterTen = arr.every((item) => item > 10);

      console.log(greaterTen); // output: false

7. reduce()

The reduce() method reduces the array to a single value.
The reduce() method executes a provided function for each value of the array (from left-to-right) and return value is stored in an accumulator.

      let arr = [1, 2, 3, 4, 5, 6];

      // adding all elements of an array
      let sum = arr.reduce((total, value) => total + value);

      console.log(sum); // output: 21

8. includes()

The includes() method determines whether an array contains a specified element.
If array contains the element, it returns 'true' otherwise 'false'.

      let arr = ["html", "css", "js"];

      // checking is array conatins 'js'
      arr.includes("js"); // output: true

      // checking is array conatins 'react'
      arr.includes("react"); // output: false

Note: All the above array methods does not change the original array.

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8 Must Know Javascript Array Methods

Shoaib Sayyed

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