1. Write a pattern which identify if a string is a valid JavaScript variable
```sh
is_valid_variable('first_name') # True
is_valid_variable('first-name') # False
is_valid_variable('1first_name') # False
is_valid_variable('firstname') # True
```
```sh
is_valid_variable('first_name') # True
is_valid_variable('first-name') # False
is_valid_variable('1first_name') # False
is_valid_variable('firstname') # True
```
### Exercises: Level 2
1. Write a function called *tenMostFrequentWords* which get the ten most frequent word from a string?
```js
paragraph = `I love teaching. If you do not love teaching what else can you love. I love Python if you do not love something which can give you all the capabilities to develop an application what else can you love.`
console.log(tenMostFrequentWords(paragraph))
```
```sh
[
{word:'love', count:6},
{word:'you', count:5},
{word:'can', count:3},
{word:'what', count:2},
{word:'teaching', count:2},
{word:'not', count:2},
{word:'else', count:2},
{word:'do', count:2},
{word:'I', count:2},
{word:'which', count:1},
{word:'to', count:1},
{word:'the', count:1},
{word:'something', count:1},
{word:'if', count:1},
{word:'give', count:1},
{word:'develop',count:1},
{word:'capabilities',count:1},
{word:'application', count:1},
{word:'an',count:1},
{word:'all',count:1},
{word:'Python',count:1},
{word:'If',count:1}]
```
```js
console.log(tenMostFrequentWords(paragraph, 10))
```
```sh
[{word:'love', count:6},
{word:'you', count:5},
{word:'can', count:3},
{word:'what', count:2},
{word:'teaching', count:2},
{word:'not', count:2},
{word:'else', count:2},
{word:'do', count:2},
{word:'I', count:2},
{word:'which', count:1}
]
```
```js
paragraph = `I love teaching. If you do not love teaching what else can you love. I love Python if you do not love something which can give you all the capabilities to develop an application what else can you love.`
console.log(tenMostFrequentWords(paragraph))
```
```sh
[
{word:'love', count:6},
{word:'you', count:5},
{word:'can', count:3},
{word:'what', count:2},
{word:'teaching', count:2},
{word:'not', count:2},
{word:'else', count:2},
{word:'do', count:2},
{word:'I', count:2},
{word:'which', count:1},
{word:'to', count:1},
{word:'the', count:1},
{word:'something', count:1},
{word:'if', count:1},
{word:'give', count:1},
{word:'develop',count:1},
{word:'capabilities',count:1},
{word:'application', count:1},
{word:'an',count:1},
{word:'all',count:1},
{word:'Python',count:1},
{word:'If',count:1}]
```
```js
console.log(tenMostFrequentWords(paragraph, 10))
```
```sh
[
{word:'love', count:6},
{word:'you', count:5},
{word:'can', count:3},
{word:'what', count:2},
{word:'teaching', count:2},
{word:'not', count:2},
{word:'else', count:2},
{word:'do', count:2},
{word:'I', count:2},
{word:'which', count:1}
]
```
### Exercises: Level 3
1. Writ a function which cleans text. Clean the following text. After cleaning, count three most frequent words in the string.
1. Write a function which cleans text. Clean the following text. After cleaning, count three most frequent words in the string.
```js
sentence = `%I $am@% a %tea@cher%, &and& I lo%#ve %tea@ching%;. There $is nothing; &as& mo@re rewarding as educa@ting &and& @emp%o@wering peo@ple. ;I found tea@ching m%o@re interesting tha@n any other %jo@bs. %Do@es thi%s mo@tivate yo@u to be a tea@cher!?`
```js
sentence = `%I $am@% a %tea@cher%, &and& I lo%#ve %tea@ching%;. There $is nothing; &as& mo@re rewarding as educa@ting &and& @emp%o@wering peo@ple. ;I found tea@ching m%o@re interesting tha@n any other %jo@bs. %Do@es thi%s mo@tivate yo@u to be a tea@cher!?`
console.log(cleanText(sentence))
```
console.log(cleanText(sentence))
```
```sh
I am a teacher and I love teaching There is nothing as more rewarding as educating and empowering people I found teaching more interesting than any other jobs Does this motivate you to be a teacher
```
```sh
I am a teacher and I love teaching There is nothing as more rewarding as educating and empowering people I found teaching more interesting than any other jobs Does this motivate you to be a teacher
```
1. Write a function which find the most frequent words. After cleaning, count three most frequent words in the string.