JS - All about String Primitive

const car = 'Lamborghini Huracan EVO'; // Similarity of strings with arrays in JS car[0]; car[car.length-1]; car.length; // From begin car.indexOf('o'); car.indexOf('Huracan'); // From end car.lastIndexOf('E'); // index(begin, end) are used to extract part of string which are then passed to slice() as argument. car.slice(car.indexOf('o')); car.slice(8); car.slice(8,15); // Extracted string length will be (end-begin) as mentioned below // String are primitives, hence immutable. Always use a data-structure to return a new string after the operation. // Extract till a particular location inside an index. car.slice(0, car.indexOf(' ')); // Extract the last word. car.slice(car.lastIndexOf(' ')); // extracts along with space car.slice(car.lastIndexOf(' ') + 1); // +1 added to exclude the space // Extract from the end using negative values car.slice(-7); car.slice(1, -1); car.slice(0, -1); function knowYourSeatLocation(seat){ const x = seat.slice(-1); if(x === 'W'){ console.log("Window Seat"); } if(x === 'M'){ console.log("Middle Seat"); } if(x === 'A'){ console.log("Aisle Seat"); } } knowYourSeatLocation('43W'); knowYourSeatLocation('12A'); knowYourSeatLocation('67M'); // Common Methods: car.toLowerCase(); car.toUpperCase(); car.trim(); car.trimStart(); car.trimEnd(); // Methods returning boolean: Very good for conditional statements. car.includes('Lambo'); car.startsWith('Lam'); car.endsWith('EVO'); // On taking user i/p convert it to lowercase before performing any operations on the text. It would eliminate a lot of error sources related to letter-case. // Usage: Converting first letter to uppercase incase user enters name in mixed case to maintain consistency // Usage: Email validation for characters esp whitespace, invalid characters etc. // String replacement: (ToBeReplaced, ReplceWith) // replace() : A case-sensitive method. Immutable Methods for functional Programming: car.replace(' ','_'); car.replaceAll(' ','_'); // Using RegEx: Target text has to be enclosed between // with flag at the end. Desired text to be passed as second argument. car.replace(/ini/g,'123456'); // .split(): split the text based on condition, return the elements in the form of an array // .join(): opposite of .split() car.split(''); // as characters car.split(' '); // as words car.split('i'); // based on a character // Destrucutring makes it easier as compared to using .slice() const name = 'Peter Parker'; const [fName, lName] = name.split(' '); fName; lName; // Adding saluttations to the name: const title = ['Mr.', fName, lName.toUpperCase()].join(' '); title; // Usage: First letter of a Name capitalization const capitalizeName = function(name){ const names = name.split(' '); const namesUpper = []; for(const n of names){ // Method 1 and Method 2 are listed below in two lines. Both work. // namesUpper.push(n[0].toUpperCase() + n.slice(1)); namesUpper.push(n.replace(n[0],n[0].toUpperCase())); } console.log(namesUpper.join(' ')); }; capitalizeName('amar akbar anthony amarjeet'); // Padding a string i.e adding certain characters until a desired length is achieved. // (DesiredLength, ToBePaddedWith) const msg = 'Welcome to JS'; msg.padStart(20,'x'); msg.padEnd(20,'x'); // Convert a no into its string form by using: String() // Another way is to add an '' to a number i.e When one operand of a + sign is string, all operands are converted into string form. // Usage: Masking certain numbers of important documents const maskedId = function(id){ const str = id + ''; const lastFour = str.slice(-4); return lastFour.padStart(str.length, '*'); } maskedId(92837483297492); maskedId('r438t7h4irgrgTAFE'); // repeat(NoOfTimeToBeRepeated) : Repeat the same text multiple times const msgText = 'Raining.\n'; msgText.repeat(5 ); const TrainsWaiting = function(x){ console.log(`There are ${x} trains waiting on the station ${'?'.repeat(x)} \n`); } TrainsWaiting(4); TrainsWaiting(16); TrainsWaiting(8); // Extract string from a long text received from an API based on some separator found in text. const data = 'Departure';