Some code to demonstrate closured variable in JavaScript.

closuredVariable.js

function hellKitchen() {
    var knd = "chef";
    
    function hellKitchen101() {
        console.log(knd);
        knd = "assistant";
    }
    
    hellKitchen101();
    console.log(knd); // I'm now an 'assistant'
}
hellKitchen();

// another example
var bankAccount = (function() {
    var transaction;
    var balance = 0;
    
    function init() {
        transaction = {
            accountHolder: "knd",
            deposit: function(amount) {
                if (amount > 0) {
                    balance += amount;
                    return balance;
                } 
    			return balance;
            },
            withdraw: function(amount) {
                if (balance - amount >= 0) {
                    balance -= amount;
                    return balance;
                }
		return balance;
            },
	    currentBalance: function() {
		return balance;
	    }
        };
    }
    
    init();
    return transaction;
})();

console.log(bankAccount.accountHolder);     // 'knd'
console.log(bankAccount.currentBalance());  // 0
console.log(bankAccount.deposit(100));      // 100
console.log(bankAccount.deposit(300));      // 400
console.log(bankAccount.withdraw(500));     // 400. Transaction couldn't proceed. 
console.log(bankAccount.withdraw(400));     // 0