JavaScript Strings (স্ট্রিং)

const a = "হ্যালো";
const b = 'হ্যালো';
const name = "রহিম";
const template = `হ্যালো ${name}!`;

console.log(template); // "হ্যালো রহিম!"

const text = "বাংলা";

console.log(text.length);   // 5
console.log(text[0]);       // ব
console.log(text.charAt(2));// ং
console.log(text.at(-1));   // া (শেষ অক্ষর)

const message = "Hello JavaScript";

console.log(message.toUpperCase()); // "HELLO JAVASCRIPT"
console.log(message.toLowerCase()); // "hello javascript"

const text = "JavaScript";

console.log(text.slice(0, 4));     // "Java"
console.log(text.slice(4));        // "Script"
console.log(text.slice(-6));       // "Script" (শেষ থেকে)
console.log(text.substring(4, 10));// "Script"

console.log("বাংলাদেশ".slice(0, 4)); // "বাংলা"

const text = "আমি JavaScript শিখছি";

console.log(text.includes("JavaScript")); // true
console.log(text.indexOf("Script"));     // 7
console.log(text.indexOf("Python"));     // -1 (নেই)
console.log(text.startsWith("আমি"));     // true
console.log(text.endsWith("শিখছি"));     // true

console.log(text.lastIndexOf("a"));      // শেষ অবস্থান

const text = "Hello World";

console.log(text.replace("World", "Bangladesh")); // "Hello Bangladesh"

// সবগুলো বদলাতে regex global
const more = "a a a";
console.log(more.replace(/a/g, "x")); // "x x x"

console.log(more.replaceAll("a", "x")); // "x x x" (আধুনিক)

const messy = "   বাংলাদেশ   ";
console.log(messy.trim());        // "বাংলাদেশ"

const id = "7";
console.log(id.padStart(3, "0")); // "007"
console.log(id.padEnd(3, "0"));   // "700"

const csv = "রহিম,করিম,সুমন";
const names = csv.split(",");
console.log(names); // ["রহিম", "করিম", "সুমন"]

const sentence = "আমি বাংলায় কোড লিখি";
console.log(sentence.split(" ")); // ["আমি", "বাংলায়", "কোড", "লিখি"]

const back = names.join(" | ");
console.log(back); // "রহিম | করিম | সুমন"

const price = 1500;
const qty = 3;

// পুরনো জোড়া
const old = "মোট দাম: " + (price * qty) + " টাকা";

// template literal
const new = `মোট দাম: ${price * qty} টাকা`;

console.log(old);  // মোট দাম: 4500 টাকা
console.log(new);  // মোট দাম: 4500 টাকা

// multiline
const html = `<div>
  <h1>নমস্কার</h1>
</div>`;