JS-高级编程-函数表达式

functionA();
function functionA() {
  console.log("Hi!")
}

let functionA = function () {
  // 函数体
};

function factorial(num) {
  if(num <= 1) {
    return 1;
  } else {
    return num * factorial(num-1);
  }
}

let otherFactorial = factorial;
factorial = null;

console.log(otherFactorial(5)); // 报错

function factorial(num) {
  if(num <= 1) {
    return 1;
  } else {
    return num * arguments.callee(num-1);
  }
}

let factorial = ( function f(num) {
  if(num <= 1) {
    return 1;
  } else {
    return num * f(num-1);
  }
});