js - regular expression(part1)

console.log("This is tutorial 46");

let reg = /harry/; // This is a regular expression literal in js

reg = /harry/g; // g means global

// reg = /harry/i; // i means case insensitive

reg = /harry/ig;

// console.log(reg);

// console.log(reg.source);

let s = "This is great code with harry and also harry bhai";

// Functions to match expressions

// 1. exec() - This function will return an array for match or null for no match

let result = reg.exec(s);

// result = reg.exec(s);

// console.log(result);

// result = reg.exec(s);

// console.log(result); ---> We can use multiple exec with global flag

// if (result) {

//     console.log(result);

//     console.log(result.input);

//     console.log(result.index);

// }

// 2. test() - Returns true or false

let result2 = reg.test(s);

// console.log(result2); --> This will only print true if the "reg" is there in the string "s"

// 3. match() - It will return an array of results or null

// let result3 = reg.match(s) ---> This is wrong!!

let result3 = s.match(reg) // ---> This is right

// console.log(result3);

// 4. search() - Returns index of first match else -1

// let result4 = reg.search(s) ---> This is wrong!!

let result4 = s.search(reg) // ---> This is right

// console.log(result4);

// 5. replace() - Returns new replaced string with all the replacements (if no flag is given, first match will be replaced)

let result5 = s.replace(reg, 'SHUBHAM');

console.log(result5);

let regex = /harry/;

let str = "hrryt is good boy with hrr";

// let result = regex.exec(str);

// console.log("result is: ",result);

// result2 = regex.test(str)

// console.log("result2 is : ", result2);

// if(regex.test(str))

// console.log("string is matched");

// else

// console.log("string not matched");

// let look into metacharacter symbol

regex = /^harrdc/; // ^ means expression will match if string starts with

regex = /harry$/; // $ at the end of the string means "string ends with"

regex = /h.rry/; //matches any one character

regex = /h*rry/; //matches any 0 or more characters

regex = /ha?rryi?t/; //? after character means that character is optional

// regex = /h\*rry/;

if(regex.test(str))

console.log("string is matched");

else

console.log("string not matched");