7.9. Exercises: Strings¶
7.9.1. Part One¶
lengthmethod returns how many characters are in a string. However, the method will NOT give us the length of a number. If
num = 1001,
undefinedrather than 4.
Use type conversion to print the length (number of digits) of an integer.
Print the number of digits in a DECIMAL value (e.g.
num = 123.45has 5 digits but a length of 6).
Modify your code to print out the length of a decimal value EXCLUDING the period.
numcould be EITHER an integer or a decimal? Add an
if/elsestatement so your code can handle both cases. (Hint: Consider the
7.9.2. Part Two¶
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:
trim()method to remove the leading and trailing whitespace, and then print the results.
Change all of the letters in the dna string to UPPERCASE and print the result.
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.
Let's use string methods to do more work on the DNA strand:
Replace the sequence
'AGG', and then print the altered strand.
Look for the sequence
indexOf(). If found print,
'CAT found', otherwise print,
'CAT NOT found'.
slice()to print out the fifth set of 3 characters (called a codon) from the DNA strand.
Use a template literal to print,
"The DNA strand is ___ characters long."
Just for fun, apply methods to
dnaand use another template literal to print,
7.9.3. Part Three¶
If we want to turn the string
'JS', we might try
Use string concatenation and two
slice()methods to print
slice(), use method chaining to accomplish the same thing.
Use bracket notation and a template literal to print,
Just for fun, try chaining 3 or more methods together, and then print the result.
Some programming languages (like Python) include a
title()method to return a string with Every Word Capitalized (e.g.
title()method, but that won't stop us! Use the string methods you know to print
'Title Case'from the string