Eloquent JS Ch10 Regular Expressions

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//EloquentJS CH10 Regex

var slash = /\//;
show("AC/DC".search(slash)); //-> 2

var asteriskOrBrace = /[\{\*]/;//finds any of the '{' or '*' chars
var story =
  "We noticed the *giant sloth*, hanging from a giant branch.";
show(story.search(asteriskOrBrace)); //-> 15

var digitSurroundedBySpace = /\s\d\s/;
show("1a 2 3d".search(digitSurroundedBySpace)); //-> 4

var notABC = /[^ABC]/;
show("ABCBACCBBADABC".search(notABC));//-> 10

//exercise. regex expression match date in format 'xx/xx/xxxx' where x's 
//are digits 
var dateformat = /\d\d\/\d\d\/\d\d\d\d/;
"born 15/11/2003 (mother Spot): White Fang".search(dateformat); //-> 5

/a+/.test("blah");//->true; matches any string that contains an 'a' char
/^a+$/.test("blah")//->false; matches pattern entirely of 'a' char

/cat/.test("concatenate"); //-> true
/\bcat\b/.test("concatenate")); //-> false ; matches 'bounded'cat'bounded'

var parenthesizedText = /\(.*\)/; //-> any charactersequence between ( )
"Its (the sloth's) claws were gigantic!".search(parenthesizedText);//-> 4


var datePattern = /\d{1,2}\/\d\d?\/\d{4}/;
"born 15/11/2003 (mother Spot): White Fang".search(datePattern); //-> 5

//exercise. pattern that matches e-mail addresses
/*Write a pattern that matches e-mail addresses. For simplicity, assume 
	that the parts before and after the @ can contain only alphanumeric 
	characters and the characters . and - (dot and dash), while the last 
	part of the address, the country code after the last dot, may only 
	contain alphanumeric characters, and must be two or three characters
 long.*/
/[\w+\.\-]\@\W+\.\w{2,3}/ //my attempt
var answer = /\b[\w\.-]+@[\w\.-]+\.\w{2,3}\b/;
answer.test("[email protected]");//-> true
answer.test("I mailt [email protected], but it didn wrok!")//-> false

var cartoonCrying = /boo(hoo+)+/i;
"Then, he exclaimed 'Boohoooohoohooo'".search(cartoonCrying)//-> 20

var holyCow = /(sacred|holy) (cow|bovine|bull|taurus)/i;
holyCow.test("Sacred bovine!"); //-?true

var parentz = "Heloom my name is (Dijon Kock Adu);"
parentz.match(/\((.*)\)/);//-> ["(Dijon Kock Adu)","Dijon Kock Adu"]

/* When given a string, this function looks for something that follows 
	the date format we saw earlier. If it can find such a date, it puts the 
	values into a Date object. Otherwise, it throws an exception. Make it 
	accept dates in which the day or month are written with only one digit.*/
function extractDate (string) {
	// extracts date out of paragraph and returns date object using regex
	pattern = /(\d\d?)\/(\d\d?)\/(\d{4})/;
	var date = string.match(pattern); //-> ['date','day', 'month', 'year']
	if(date!=null)  {
		return new Date(+date[3],+date[2]-1,+date[2]);	
	} else {
		throw new Error("No date found in '"+ string + "'.");
	}
}//answered pretty good

// Replace method example when second argument is a string - Neat Trick
function eatOne(match, amount, unit) {
  amount = Number(amount) - 1;
  if (amount == 1) {
    unit = unit.slice(0, unit.length - 1);
  }
  else if (amount == 0) {
    unit = unit + "s";
    amount = "no";
  }
  return amount + " " + unit;
}

var stock = "1 lemon, 2 cabbages, and 101 eggs";
stock = stock.replace(/(\d+) (\w+)/g, eatOne);

print(stock);//-> no lemons, 1 cabbage, and 100 eggs