Top 5 must know JS functions

JavaScript has several top-level built-in functions. Let's have a look at

1. Spread Operator

The Spread Operator expands an array into its elements. It can also be used for object literals.

const foodList = ['pizza','fries','samosa'];
console.log(...foodList);
// Output : pizza fries samosa

2. Filter()

The filter() method creates a new array with all elements that pass the test.

const prices = [25,30,125,34,50];
prices.filter(function(price){
  return price >= 30;
});
// Output : [30,125,34,50]

3. Map()

The map() method is similar to the filter() method in terms of returning a new array. However, the only difference is that it is used to modify items.

const productPriceList = [200,350,1500,5000];
productPriceList.map(function(item){
 return item * 0.75;
});
// Output : [150,262.5,1125,3750]

4. Reduce()

The reduce() method can be used to transform an array into something else, which could be an integer, an object, a chain of promises. Eg : To sum a list of integers. In Short, it "reduces" the whole array into one value.
```
const weeklyExpenses = [200,350,1500,5000,450,680,350]
weeklyExpenses.reduce(function(first,last){
 return first+last;
});
// Output : 8530
```

5. Includes()

The included() method is used to check if a specific string exists in a collection, and returns true or false.

const garage = ['BMW','AUDI','VOLVO'];
const findCar = garage.includes('BMW');
console.log(findCar);
// Output : true

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Top 5 Must Known JS Functions