Javascript：如何将声明的函数存储在变量中？

Question

I'm learning Javascript and wondering if it's possible to store a declared function in a variable to be used later?

For context,

function add(a, b) {
   return a + b;
}

var addTogether = _.partial(add, 1);

doSomething() // returns a promise that resolves to a 2
  .then(addTogether); // expect to return 3

Is there a way to achieve this?

Answer 1

var Add = function (a, b)
{
    return a + b;
}

var result = Add (2, 3);

Answer 2

Absolutely. Functions ARE data in JavaScript.

var foo = function(a, b) {
   return a + b;
}

Is perfectly legitimate.

  function add(a, b) { return a + b; } var foo = add; console.log(foo(5,10)); console.log(add(10, 20)); 

Answer 3

You can also use ES6 syntax to store anonymous functions in constants, like so:

const add = (a, b) => a + b;
const addOne = a => add(a, 1);

console.log(add(5, 10)); // 15
console.log(addOne(5));  // 6