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📝 字数：working on

Variables and Strings

Estimated time to read: 1 minute

Concepts

Introduction to JavaScript

  • HTML provides structure, CSS adds styling, and JavaScript enables behavior, creating a complete and interactive web experience.

  • A data type is the kind of value you store.

  • Number

    • Infinity

    • NaN

  • String

  • Boolean

  • undefined

  • null: a special type of Object, 

    let exampleVariable = null;
console.log(typeof exampleVariable); // "object"

  • Object: collection of key-value pairs

  • Symbol: unique and immutable

  • BigInt

  • ASI: Automatic Semicolon Insertion

Code

let _$aGeFrom = 25; // initialization
age = 30; // reassignment
const immutable = value;
const sentenceStr = "can't change by index, alter"; 
let sentenceStrM = "can resign";
sentenceStrM = "resign";
// string concatenation: +, +=, concat()
let result = str1.concat(' ', str2);
// typeof operator
console.log(typeof num);

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