# 7.9. Exercises: Strings¶

## 7.9.1. Part One¶

1. The `length` method returns how many characters are in a string. However, the method will NOT give us the length of a number. If `num = 1001`, `num.length` returns `undefined` rather than 4.

1. Use type conversion to print the length (number of digits) of an integer.

2. Print the number of digits in a DECIMAL value (e.g. `num = 123.45` has 5 digits but a length of 6).

1. Modify your code to print out the length of a decimal value EXCLUDING the period.

3. What if `num` could be EITHER an integer or a decimal? Add an `if/else` statement so your code can handle both cases. (Hint: Consider the `indexOf()` or `includes()` string methods).

Code it at repl.it

## 7.9.2. Part Two¶

1. Remember, strings are immutable. Consider a string that represents a strand of DNA: `dna = " TCG-TAC-gaC-TAC-CGT-CAG-ACT-TAa-CcA-GTC-cAt-AGA-GCT    "`. There are some typos in the string that we would like to fix:

1. Use the `trim()` method to remove the leading and trailing whitespace, and then print the results.

2. Change all of the letters in the dna string to UPPERCASE and print the result.

3. Note that if you try `console.log(dna)` after applying the methods, the original, flawed string is displayed. To fix this, you need to reassign the changes back to `dna`. Apply these fixes to your code so that `console.log(dna)` prints the DNA strand in UPPERCASE with no whitespace.

Code it at repl.it

2. Let's use string methods to do more work on the DNA strand:

1. Replace the sequence `'GCT'` with `'AGG'`, and then print the altered strand.

2. Look for the sequence `'CAT'` with `indexOf()`. If found print, ```'CAT found'```, otherwise print, `'CAT NOT found'`.

3. Use `slice()` to print out the fifth set of 3 characters (called a codon) from the DNA strand.

4. Use a template literal to print, `"The DNA strand is ___ characters long."`

5. Just for fun, apply methods to `dna` and use another template literal to print, `'taco cat'`.

Code it at repl.it

## 7.9.3. Part Three¶

1. If we want to turn the string `'JavaScript'` into `'JS'`, we might try `.remove()`. Unfortunately, there is no such method in JavaScript. However, we can use our cleverness to achieve the same result.

1. Use string concatenation and two `slice()` methods to print `'JS'` from `'JavaScript'`.

2. Without using `slice()`, use method chaining to accomplish the same thing.

3. Use bracket notation and a template literal to print, ```"The abbreviation for 'JavaScript' is 'JS'."```

4. Just for fun, try chaining 3 or more methods together, and then print the result.

Code it at repl.it

2. Some programming languages (like Python) include a `title()` method to return a string with Every Word Capitalized (e.g. `'title case'.title()` returns `Title Case`). JavaScript has no `title()` method, but that won't stop us! Use the string methods you know to print `'Title Case'` from the string `'title case'`.

Code it at repl.it