//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(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...
```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:
@ -261,7 +261,7 @@ console.log(randomNumRoundToFloor) // this gives between 0 and 10
## 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:
```js
@ -272,12 +272,13 @@ let country = 'Finland'
let city = 'Helsinki'
let language = 'JavaScript'
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
Connecting two or more strings together is called concatenation.
Using the strings declared in the previous String section:
```js
@ -305,8 +306,9 @@ let city = 'Helsinki'
let language = 'JavaScript'
let job = 'teacher'
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
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.\
Now, we are in 2020. I am enjoying preparing the 30DaysOfJavaScript challenge and \
I hope you are enjoying too."
console.log(paragraph)
```
@ -341,7 +344,7 @@ In JavaScript and other programming languages \ followed by some characters is a
- \t: Tab, means 8 spaces
- \\\\: Back slash
- \\': Single quote (')
- \\":Double quote (")
- \\":Double quote (")
```js
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)
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
//Syntax
@ -528,17 +531,17 @@ console.log(country.substring(3)) // land
```js
let string = '30 Days Of JavaScript'
console.log(string.split()) // ["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
```js
string.indexOf(substring)
```
@ -704,11 +705,11 @@ string.endsWith(substring)
```
```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('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
string.search(substring)
@ -726,6 +727,7 @@ string.search(substring)
```js
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(/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.
@ -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.
```
2. Using console.log() print out the following quote by Mother Teresa:
```sh
@ -955,6 +956,7 @@ console.log(numInt) // 9
4 1 4 16 64
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'__
Asabeneh
5 years ago