JavaScript - string

console.log("// ----------------- Strings ----------------------");
console.log("///////////////////////////////////////////////////");

// 1. declaration and assignment
// 2. string literals. defining single line and multi-line string literals
// 3. functions: length, toLowerCase, toUpperCase, substring, trim, concat, indexOf, lastIndexOf, charAt
// 4. using string as array - for reading. since ES5
// 5. comparing strings
// 6. primitive string and String object. How to create each? use typeof to see, what is difference. what to prefer.
// 7. auto-boxing: Automatic conversion of primitive to String object depending on context
// 8. primitive is pointer to a row memory location i.e. fast speed/random-access
// 9. they are not same e.g. eval method takes expression in primitive string
// 10. use instance and typeof to check each case
// 11. converting one form to another. e.g. new keyword and valueof method

lastName = "Shahzad";
console.log(lastName);
console.log(typeof lastName);
console.log(lastName.length);
console.log("Trimmed ..." + lastName.trim());
console.log(lastName.concat("Ali"));
console.log(lastName.indexOf("h"));
console.log(lastName.lastIndexOf("a"));
console.log("Length = " + lastName.length);
console.log("Last Name " + lastName);
console.log("charAt 1 = " + lastName.charAt(1));

// multiline string literals
let description = "data can be placed here \
and other can be written in next row \
in same wa";

// Using string as array (since ES 5). for reading
console.log(lastName[1]);

// Comparing string
let name1 = 'a';
let name2 = 'b';

if (name1 < name2) 
  console.log(name1 + " is less than" + name2);
else 
  console.log(name1 + " is greater or equal " + name2);

// if one operand is primitive, other would be unboxed too before comparison
if(name1 == name2)
  console.log('== equal');
else 
  console.log('== not equal');

if (name1.localeCompare(name2) == 0) 
  console.log("equal");
else 
  console.log("not equal ... ");

// string primitive and String object

let degree1 = String("BSCS");
let degree2 = new String("MSCS");
console.log("type = " + typeof degree1);
console.log("type = " + typeof degree2);
console.log(degree1 + " and " + degree2); // implicit unboxing for degree2

console.log(eval("2+2")); // eval works on primitive string
console.log(eval(new String("2+2")));

if (degree1 instanceof String) 
  console.log("Its instance of string");
else 
  console.log("Its not an instance of string");

// convert one form to another.
// primitive to object

let std1 = new String("Ali");
// object to primitive
let std2 = std1.valueOf();