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30-Days-Of-JavaScript
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Asabeneh 6 years ago
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02_Day/02_day_data_types.md
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@ -160,12 +160,19 @@ In JavaScript the Math Object provides a lots of methods to work with numbers.
```js
const PI = Math.PI
console.log(PI) // 3.141592653589793
// Rounding to the closest number
// if above .5 up if less 0.5 down rounding
console.log(Math.round(PI)) // 3; to round values to the nearest number
console.log(Math.round(9.81)) // 10
console.log(Math.floor(PI)) // 3; rounding down
console.log(Math.ceil(PI)) // 4; rounding up
console.log(Math.min(-5, 3, 20, 4,5, 10)) // -5, returns the minimum value
console.log(Math.max(-5, 3, 20, 4,5, 10)) // 20, returns the maximum value
const randNum = Math.random() // creates random number between 0 to 0.999999
@ -198,7 +205,7 @@ Math.cos(60)
#### Random number generator
The JavaScript Math Object has a random() method number generator which generators number from 0 to 0.999999999...
The JavaScript Math Object has a random() method number generator which generates number from 0 to 0.999999999...
```js
let randomNum = Math.random() // generates 0 to 0.999
@ -396,12 +403,17 @@ Let us access different characters in 'JavaScript' string.
```js
let string = 'JavaScript'
let firstLetter = string[0]
console.log(firstLetter) // J
let secondLetter = string[1] // a
let thirdLetter = string[2]
let lastLetter = string[9]
console.log(lastLetter) // t
let lastIndex = string.length - 1
console.log(lastIndex) // 9
console.log(string[lastIndex]) // t
```
@ -410,10 +422,15 @@ console.log(string[lastIndex]) // t
```js
let string = 'JavaScript'
console.log(string.toUpperCase()) // JAVASCRIPT
let firstName = 'Asabeneh'
console.log(firstName.toUpperCase()) // ASABENEH
let country = 'Finland'
console.log(country.toUpperCase()) // FINLAND
```
@ -421,10 +438,15 @@ console.log(country.toUpperCase()) // FINLAND
```js
let string = 'JavasCript'
console.log(string.toLowerCase()) // javascript
let firstName = 'Asabeneh'
console.log(firstName.toLowerCase()) // asabeneh
let country = 'Finland'
console.log(country.toLowerCase()) // finland
```
@ -433,6 +455,7 @@ console.log(country.toLowerCase()) // finland
```js
let string = 'JavaScript'
console.log(string.substr(4,6)) // Script
let country = 'Finland'
console.log(country.substr(3, 4)) // land
```
@ -441,10 +464,13 @@ console.log(country.substr(3, 4)) // land
```js
let string = 'JavaScript'
console.log(string.substring(0,4)) // Java
console.log(string.substring(4,10)) // Script
console.log(string.substring(4)) // Script
let country = 'Finland'
console.log(country.substring(0, 3)) // Fin
console.log(country.substring(3, 7)) // land
console.log(country.substring(3)) // land
@ -454,12 +480,17 @@ console.log(country.substring(3)) // land
```js
let string = '30 Days Of JavaScipt'
console.log(string.split()) // ["30 Days Of JavaScript"]
console.log(string.split(' ')) // ["30", "Days", "Of", "JavaScript"]
let firstName = 'Asabeneh'
console.log(firstName.split()) // ["Asabeneh"]
console.log(firstName.split('')) // ["A", "s", "a", "b", "e", "n", "e", "h"]
let countries = 'Finland, Sweden, Norway, Denmark, and Iceland'
console.log(countries.split(',')) // ["Finland", " Sweden", " Norway", " Denmark", " and Iceland"]
console.log(countries.split(', ')) //  ["Finland", "Sweden", "Norway", "Denmark", "and Iceland"]
```
@ -468,11 +499,14 @@ console.log(countries.split(', ')) //  ["Finland", "Sweden", "Norway", "Denma
```js
let string = ' 30 Days Of JavaScript '
console.log(string)
console.log(string.trim(' ')) //
console.log(string.trim(' '))
let firstName = ' Asabeneh '
console.log(firstName)
console.log(firstName.trim()) //
console.log(firstName.trim())
```
```sh
@ -486,6 +520,7 @@ Asabeneh
```js
let string = '30 Days Of JavaScript'
console.log(string.includes('Days')) // true
console.log(string.includes('days')) // false
console.log(string.includes('Script')) // true
@ -494,6 +529,7 @@ console.log(string.includes('java')) // false
console.log(string.includes('Java')) // true
let country = 'Finland'
console.log(country.includes('fin')) // false
console.log(country.includes('Fin')) // true
console.log(country.includes('land')) // true
@ -509,6 +545,7 @@ string.replace(oldsubstring, newsubstring)
```js
let string = '30 Days Of JavaScript'
console.log(string.replace('JavaScript', 'Python')) // 30 Days Of Python
let country = 'Finland'
console.log(country.replace('Fin', 'Noman')) // Nomanland
```
@ -522,6 +559,7 @@ string.charAt(index)
```js
let string = '30 Days Of JavaScript'
console.log(string.charAt(0)) // 3
let lastIndex = string.length - 1
console.log(string.charAt(lastIndex)) // t
```
@ -535,6 +573,7 @@ string.charCodeAt(index)
```js
let string = '30 Days Of JavaScript'
console.log(string.charCodeAt(3)) // D ASCII number is 51
let lastIndex = string.length - 1
console.log(string.charCodeAt(lastIndex)) // t ASCII is 116
@ -548,6 +587,7 @@ string.indexOf(substring)
```js
let string = '30 Days Of JavaScript'
console.log(string.indexOf('D')) // 3
console.log(string.indexOf('Days')) // 3
console.log(string.indexOf('days')) // -1
@ -565,6 +605,7 @@ string.lastIndexOf(index)
```js
let string = 'I love JavaScript. If you do not love JavaScript what else can you love.'
console.log(string.lastIndexOf('love')) // 67
console.log(string.lastIndexOf('you')) // 63
console.log(string.lastIndexOf('JavaScript')) // 38
@ -579,6 +620,7 @@ string.concat(substring, substring, substring)
```js
let string = '30'
console.log(string.concat("Days", "Of", "JavaScript")) // 30DaysOfJavaScript
let country = 'Fin'
console.log(country.concat("land")) // Finland
```
@ -592,11 +634,13 @@ string.startsWith(substring)
```js
let string = 'Love is the best to in this world'
console.log(string.startsWith('Love')) // true
console.log(string.startsWith('love')) // false
console.log(string.startsWith('world')) // false
let country = 'Finland'
console.log(country.startsWith('Fin')) // true
console.log(country.startsWith('fin')) // false
console.log(country.startsWith('land')) // false
@ -610,11 +654,13 @@ string.endsWith(substring)
```js
let string = 'Love is the best to in this world'
console.log(string.endsWith('world')) // true
console.log(string.endsWith('love')) // false
console.log(string.endsWith('in this world')) // true
let country = 'Finland'
console.log(country.endsWith('land')) // true
console.log(country.endsWith('fin')) // false
console.log(country.endsWith('Fin')) // false
@ -699,8 +745,8 @@ let firstName = 'Asabeneh' // string
let lastName = 'Yetayeh' // string
let country = 'Finland' // string
let city = 'Helsinki' // string
let age = 250 // int, it is not my real age, do not worry about it
let job
let age = 250 // number, it is not my real age, do not worry about it
let job // undefined, because a value was not assigned
console.log(typeof 'Asabeneh') // string
console.log(typeof firstName) // string
@ -726,7 +772,7 @@ We can convert string to number using the following methods:
- parseInt()
- Number()
- +
- Plus sign(+)
```js
let num = '10'
@ -737,12 +783,14 @@ console.log(numInt) // 10
```js
let num = '10'
let numInt = Number(num)
console.log(numInt) // 10
```
```js
let num = '10'
let numInt = +num
console.log(numInt) // 10
```
@ -753,23 +801,26 @@ We can convert string float to number using the following methods:
- parseFloat()
- Number()
- +
- Plus sign(+)
```js
let num = '9.81'
let numFloat = parseFloat(num)
console.log(numFloat) // 9.81
```
```js
let num = '9.81'
let numFloat = Number(num)
console.log(numFloat) // 9.81
```
```js
let num = '9.81'
let numFloat = +num
console.log(numInt) // 9.81
```
@ -783,6 +834,7 @@ We use the following method to convert float to int:
```js
let num = 9.81
let numInt = parseInt(num)
console.log(numInt) // 9
```

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