Merge pull request #65 from wakidurrahman/feat/string-03

Regular Expressions

Author: wakidurrahman

src/exercises/regular-expressions/regular-expressions-101.ts

@@ -0,0 +1,61 @@
+/**
+ * Regular Expressions
+ *
+ * Regular expressions (regexes) are a set of characters that define a search pattern.
+ *
+ * The constructor for the RegExp object takes two parameters:
+ * the regular expression and the optional match settings, as shown here:
+ *
+ * i ==> Perform case-insensitive matching
+ * g ==> Perform a global match (find all matches rather than stopping after first match)
+ * m ==> Perform multiline matching
+ *
+ * RegExp has the following two functions:
+ * 1. search(): Tests for matches in a string. This returns the index of the match.
+ * 2. match(): Tests for matches. This returns all the matches.
+ *
+ * The JavaScript String object also has the following two regex-related functions that accept the RegExp object as an argument:
+ * 1. exec(): Tests for matches in a string. This returns the first match.
+ * 2. test(): Tests for matches in a string. This returns true or false.
+ */
+
+// The following are five regexes that developers often use.
+
+// 1. Any Numeric Characters
+const numeric = /\d+/;
+numeric.test('123444'); // returns true
+numeric.test('333ass'); // returns true
+numeric.test('5asdasd'); // returns true
+numeric.test('asdasd'); // returns false
+
+// 2. Only Numeric Characters
+const onlyNumeric = /^\d+$/;
+onlyNumeric.test('123'); // true
+onlyNumeric.test('123a'); // false
+onlyNumeric.test('a'); // false
+
+// 3. Floating Numeric Characters
+const floatNumeric = /^[0-9]*.[0-9]*[1-9]+$/;
+
+floatNumeric.test('12'); // true
+floatNumeric.test('1'); // false
+floatNumeric.test('12.3'); // true
+
+// 4. Only Alpha Numeric Characters
+const alphaNumeric = /[a-zA-Z0-9]/;
+alphaNumeric.test('somethingELSE'); // true
+alphaNumeric.test('hello'); // true
+alphaNumeric.test('112a'); // true
+alphaNumeric.test('112'); // true
+alphaNumeric.test('^'); // false
+
+// 5. Query String
+
+const url = 'http://your.domain/product.aspx?category=4&product_id=2140&query=lcd+tv';
+let queryString = {};
+url.replace(new RegExp('([^?=&]+)(=([^&]*))?', 'g'), function ($0, $1, $2, $3) {
+  queryString[$1] = $3;
+});
+console.log(queryString);
+
+// http://your.domain/product.aspx: undefined, category: '4', product_id: '2140', query: 'lcd+tv'