To find all elements of an array satisfying a condition in JavaScript - ECMAScript 2021, you can use the Array.prototype.filter method, which creates a new array with all elements that pass the specified condition.
The syntax for Array.prototype.filter is as follows:
const newArray = array.filter(function(element) {
// Condition to be checked
});
Here newArray is the new array returned by the filter() method, array is the original array, and element is the current element being processed.
For example, let's say we have an array of numbers and we want to find all even numbers from it. We can use the filter() method to achieve it as below:
const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9];
const evenNumbers = numbers.filter(function(number) {
return number % 2 === 0;
});
console.log(evenNumbers); // Output: [2, 4, 6, 8]
In this example, we passed a function to filter() that checks if the element is even or not. If the element is even, it returns true, else false. The filter() method creates a new array evenNumbers containing only the even numbers from the original array numbers.
You can also use arrow function expression syntax to achieve the same result as follows:
const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9];
const evenNumbers = numbers.filter((number) => number % 2 === 0);
console.log(evenNumbers); // Output: [2, 4, 6, 8]
In this syntax, you can use shorthand () => {} syntax to define the callback function for the filter() method.
This is how you can find all elements of an array satisfying a condition in JavaScript - ECMAScript 2021.