//Returns the natural logarithm with base E of x, Math.log(x)
//Returns the natural logarithm with base E of x, Math.log(x)
console.log(Math.log(2)) // 0.6931471805599453
console.log(Math.log(2)) // 0.6931471805599453
console.log(Math.log(10)) // 2.302585092994046
console.log(Math.log(10)) // 2.302585092994046
@ -244,7 +244,7 @@ Math.cos(60)
The JavaScript Math Object has a random() method number generator which generates 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
```js
let randomNum = Math.random() // generates 0 to 0.999
let randomNum = Math.random() // generates 0 to 0.999...
```
```
Now, let us see how we can use random() method to generate a random number between 0 and 10:
Now, let us see how we can use random() method to generate a random number between 0 and 10:
@ -261,7 +261,7 @@ console.log(randomNumRoundToFloor) // this gives between 0 and 10
## Strings
## Strings
Strings are texts, which are under **_single_**or **_double_** quote. To declare a string, we need a variable name, assignment operator, a value under a single quote, double quote, or backtick quote.
Strings are texts, which are under **_single_** , **_double_**, **_back-tick_** quote. To declare a string, we need a variable name, assignment operator, a value under a single quote, double quote, or backtick quote.
Let's see some examples of strings:
Let's see some examples of strings:
```js
```js
@ -272,12 +272,13 @@ let country = 'Finland'
let city = 'Helsinki'
let city = 'Helsinki'
let language = 'JavaScript'
let language = 'JavaScript'
let job = 'teacher'
let job = 'teacher'
let quote = "The saying,'Seeing is Believing' is not correct in 2020."
let quotWithBackTick = `The saying,'Seeing is Believing' is not correct in 2020.`
```
```
### String Concatenation
### String Concatenation
Connecting two or more strings together is called concatenation.
Connecting two or more strings together is called concatenation.
Using the strings declared in the previous String section:
Using the strings declared in the previous String section:
```js
```js
@ -305,8 +306,9 @@ let city = 'Helsinki'
let language = 'JavaScript'
let language = 'JavaScript'
let job = 'teacher'
let job = 'teacher'
let age = 250
let age = 250
let fullName = firstName.concat(space).concat(lastName) // concat string method
let fullName =firstName + space + lastName
let personInfoOne = fullName + '. I am ' + age + '. I live in ' + country; // ES5 string addition
let personInfoOne = fullName + '. I am ' + age + '. I live in ' + country; // ES5 string addition
console.log(personInfoOne)
console.log(personInfoOne)
@ -330,6 +332,7 @@ to global audience and I started a Python challenge from November 20 - December
It was one of the most rewarding and inspiring experience.\
It was one of the most rewarding and inspiring experience.\
Now, we are in 2020. I am enjoying preparing the 30DaysOfJavaScript challenge and \
Now, we are in 2020. I am enjoying preparing the 30DaysOfJavaScript challenge and \
I hope you are enjoying too."
I hope you are enjoying too."
console.log(paragraph)
console.log(paragraph)
```
```
@ -341,7 +344,7 @@ In JavaScript and other programming languages \ followed by some characters is a
- \t: Tab, means 8 spaces
- \t: Tab, means 8 spaces
- \\\\: Back slash
- \\\\: Back slash
- \\': Single quote (')
- \\': Single quote (')
- \\":Double quote (")
- \\":Double quote (")
```js
```js
console.log('I hope everyone is enjoying the 30 Days Of JavaScript challenge.\nDo you ?') // line break
console.log('I hope everyone is enjoying the 30 Days Of JavaScript challenge.\nDo you ?') // line break
@ -374,7 +377,7 @@ The saying 'Seeing is Believing' isn't correct in 2020
#### Template Literals (Template Strings)
#### Template Literals (Template Strings)
To create a template strings, we use two backticks. We can inject data as expressions inside a template string. To inject data, we enclose the expression with a curly bracket({}) preceded by a $ sign. See the syntax below.
To create a template strings, we use two back-ticks. We can inject data as expressions inside a template string. To inject data, we enclose the expression with a curly bracket({}) preceded by a $ sign. See the syntax below.
```js
```js
//Syntax
//Syntax
@ -528,17 +531,17 @@ console.log(country.substring(3)) // land
```js
```js
let string = '30 Days Of JavaScript'
let string = '30 Days Of JavaScript'
console.log(string.split()) // ["30 Days Of JavaScript"]
console.log(string.split()) // Changes to an array -> ["30 Days Of JavaScript"]
@ -626,10 +629,8 @@ console.log(string.charCodeAt(lastIndex)) // t ASCII is 116
```
```
13. *indexOf()*: Takes a substring and if the substring exists in a string it returns the first position of the substring if does not exist it returns -1
13. *indexOf()*: Takes a substring and if the substring exists in a string it returns the first position of the substring if does not exist it returns -1
```js
```js
string.indexOf(substring)
string.indexOf(substring)
```
```
@ -704,11 +705,11 @@ string.endsWith(substring)
```
```
```js
```js
let string = 'Love is the best to in this world'
let string = 'Love is the most powerful feeling in the world'
console.log(string.endsWith('world')) // true
console.log(string.endsWith('world')) // true
console.log(string.endsWith('love')) // false
console.log(string.endsWith('love')) // false
console.log(string.endsWith('in this world')) // true
console.log(string.endsWith('in the world')) // true
18. *search*: it takes a substring as an argument and it returns the index of the first match.
18. *search*: it takes a substring as an argument and it returns the index of the first match. The search value can be a string or a regular expression pattern.
```js
```js
string.search(substring)
string.search(substring)
@ -725,7 +726,8 @@ string.search(substring)
```js
```js
let string = 'I love JavaScript. If you do not love JavaScript what else can you love.'
let string = 'I love JavaScript. If you do not love JavaScript what else can you love.'
console.log(string.search('love')) // 2
console.log(string.search('love')) // 2
console.log(string.search(/javascript/gi)) // 7
```
```
19. *match*: it takes a substring or regular expression pattern as an argument and it returns an array if there is match if not it returns null. Let us see how a regular expression pattern looks like. It starts with / sign and ends with / sign.
19. *match*: it takes a substring or regular expression pattern as an argument and it returns an array if there is match if not it returns null. Let us see how a regular expression pattern looks like. It starts with / sign and ends with / sign.
20. *repeat()*: it takes a number as argument and it returns the repeated version of the string.
20. *repeat()*: it takes a number as argument and it returns the repeated version of the string.
```js
```js
string.repeat(n)
string.repeat(n)
@ -931,7 +933,6 @@ console.log(numInt) // 9
The quote 'There is no exercise better for the heart than reaching down and lifting people up.' by John Holmes teaches us to help one another.
The quote 'There is no exercise better for the heart than reaching down and lifting people up.' by John Holmes teaches us to help one another.
```
```
2. Using console.log() print out the following quote by Mother Teresa:
2. Using console.log() print out the following quote by Mother Teresa:
```sh
```sh
@ -955,6 +956,7 @@ console.log(numInt) // 9
4 1 4 16 64
4 1 4 16 64
5 1 5 25 125
5 1 5 25 125
```
```
12. Use __substr__ to slice out the phrase __because because because__ from the following sentence:__'You cannot end a sentence with because because because is a conjunction'__
12. Use __substr__ to slice out the phrase __because because because__ from the following sentence:__'You cannot end a sentence with because because because is a conjunction'__
Asabeneh
5 years ago