Одинаковые имена аргументов и параметров функций

var balance = 10500;
 
function steal(balance, amount) {
if (amount < balance) {
balance = balance - amount;
}
return amount;
}
 
var amount = steal(balance, 1250);
alert("Criminal: you stole " + amount + "!");

var balance = 105000; 
function steal(balance, amount){if(amount<balance) return balance-amount; return amount} 
var amount=steal(balance, 1250);
console.log("Criminal: you stole " + amount + "!");

var a=5,b=7;
function foo(a, b) {
  var sum = a + b;
  alert(sum);
}
foo(a,b) // 12

var balance = 10500;
 
// WARN: variable shadowing `balance`
function steal(balance, amount) {
  if (amount < balance) {
    // эта операция никак не повлияет на глобальную `balance`
    balance = balance - amount;
  }
  return amount;
}
 
alert('Balance is ' + balance); // => 10500
var amount = steal(balance, 1250);
alert("Criminal: you stole " + amount + "!");
alert('Balance is still ' + balance); // => 10500

var balance = {
    size: 10500
};
 
function steal(balance, amount) {
  if (amount < balance.size) {
    balance.size -= amount;
  }
  return amount;
}
 
alert('Balance is ' + balance.size); // => 10500
var amount = steal(balance, 1250);
alert("Criminal: you stole " + amount + "!");
alert('Balance is ' + balance.size); // => 9250

var balance = {
  size: 10500
};
 
function steal(balance, amount) {
  if (amount < balance.size) {
    balace = {
      size: balance.size - amount
    }
  }
  return amount;
}
 
alert('Balance is ' + balance.size); // => 10500
var amount = steal(balance, 1250);
alert("Criminal: you stole " + amount + "!");
alert('Balance is still ' + balance.size); // => 10500