Some of JavaScript's Built-In Methods
Published: 2021-10-11 02:45:23

Is JavaScript confusing? It can be, sure. But it’s pretty amazing, especially with it’s built-in methods that can reduce the amount of code written and help with readability. Here a few JS built-in methods that you’re probably already using or have at least seen more than once. 

**Concat()**- this method will join two (or more) strings together and return a new string. 

```javascript
let str = "Hey there! "
let str2 = "JavaScript is fun."

console.log(str.concat(str2)) // "Hey there! JavaScript is fun.”
```

**Length()**- this method will return the length of the given string. 

```javascript
let str = "Hey there!"
let str2 = "JavaScript is fun."

console.log(str.length) // 10
console.log(str2.length) // 18
```

**ToUpperCase()**- converts the given string to uppercase. 

```javascript
let str = "Hey there! JavaScript is fun."

console.log(str.toUpperCase()) // "HEY THERE! JAVASCRIPT IS FUN."
```

**ToLowerCase()**- converts the given string to lowercase. 

```javascript
let str = "Hey there! JavaScript is fun."

console.log(str.toLowerCase()) // "hey there! javascript is fun."
```

**Split()**- splits the string into substrings which are placed in an array and using a separator you choose. 

```javascript
let str = "Hey there! JavaScript is fun."

console.log(str.split('')) // ["H", "e", "y", " ", "t", "h", "e", "r", "e", "!", " ", "J", "a", "v", "a", "S", "c", "r", "i", "p", "t", " ", "i", "s", " ", "f", "u", "n", "."]
// here the string is spilt into characters, using no space as a separator

console.log(str.split(' ')) // ["Hey", "there!", "JavaScript", "is", "fun."] 
// here the string is split into separate strings using a space as the separator
```

**Join()**- joins an arrays elements and returns a new string, as with split you can choose your separator. 

```javascript
let greetings = ["Hi", "Hello", "Hey"]

console.log(greetings.join('')) // “HiHelloHey"
// here the elements are joined with no space as the separator

console.log(greetings.join(' ')) // " Hi Hello Hey”
// here the elements are joined with a space as the separator
```

**Reverse()**- reverses the order of the given array’s elements. 

```javascript
let animals = ["Lions", "Tigers", "Bears"]

console.log(animals.reverse()) // ["Bears", "Tigers", “Lions"]
```

**Pop()**- removes the last element of the given array and returns it. 

```javascript
let animals = ["Lions", "Tigers", "Bears"]

console.log(animals.pop()) // "Bears"
```

**Push()**- adds one or more elements to the end of the given array and returns the new length of that array. (If you log the array to the console again, you’ll see your element(s) are now added)

```javascript
let animals = ["Lions", "Tigers", "Bears"]

console.log(animals.push("Monkies")) // 4
console.log(animals) // ["Lions", "Tigers", "Bears", "Monkies"]
```

**Shift()**- removes the first element of the given array and returns it. 

```javascript
let animals = ["Lions", "Tigers", "Bears"]

console.log(animals.shift()) // "Lions"
```

**Unshift()**- adds one or more elements to the beginning of the given array and returns the new length of that array. (If you log the array to the console again, you’ll see your element(s) are now added)

```javascript
let animals = ["Lions", "Tigers", "Bears"]

console.log(animals.unshift("Monkies")) // 4
console.log(animals) // ["Monkies", "Lions", "Tigers", “Bears"]
```

These are just a few of the built-in methods JavaScript gives us for free. If you want to see more I suggest checking out [MDN](https://developer.mozilla.org/en-US/) for a more comprehensive list. Thanks for reading!