[]实现柯里化函数

时间：2021-2-1 Mon
done

实现sum(1)(2)(3)(4).sumOf();

:::success 实现 sum 函数使得以下表达式的值正确
sum(1, 2, 3).sumOf(); //6
sum(2, 3)(2).sumOf(); //7
sum(1)(2)(3)(4).sumOf(); //10
sum(2)(4, 1)(2).sumOf(); //9 :::

区别： sumOf终止， 参数数量不限

arguments.slice() is not a funtion
正确写法：

⚠️ return fn应放在底部
⚠️ fn.prototype.sumOf 错误， fn.sumOf正确

function sum() {
  let args = Array.prototype.slice.call(arguments)
  let sum = args.reduce((a, c) => a + c, 0);
  function fn () {
    let args2 = Array.prototype.slice.call(arguments);
    sum += args2.reduce((a, c) => a + c, 0);
    return fn
  }
  fn.sumOf = function () {
    return sum;
  }
  return fn;  // 注意， 必须放在底部
}
console.log(sum(1, 2, 3).sumOf()) // 6
console.log(sum(1, 2, 3)(4, 5).sumOf()) // 15
console.log(sum(2, 3)(2).sumOf()) // 7
console.log(sum(1)(2)(3)(4).sumOf()) // 10
console.log(sum(2)(4, 1)(2).sumOf()) // 9

实现curriedSum(1)(2)(3)

:::success //1.手写函数柯里化
function curry(func) {
//此处补全
}
function sum(a, b, c) {
return a + b + c;
}

let curriedSum = curry(sum);

alert(curriedSum(1, 2, 3)); // 6, still callable normally
alert(curriedSum(1)(2, 3)); // 6, currying of 1st arg
alert(curriedSum(1)(2)(3)); // 6, full currying :::

区别：参数固定， 参数传入顺序无关

实现

//1.手写函数柯里化
function curry(func, args) {
    const n = func.length;
    args = args || [];
    return function (...rest) {
        var _args = [...args, ...rest];
          if (_args.length < n) {
          return curry.call(this, func, _args);
        } else {
            return func.apply(this, _args);
        }
    }
  }
  function sum(a, b, c) { 
    return a + b + c;
  }
  let curriedSum = curry(sum);
  console.log(curriedSum(1, 2, 3)); // 6, still callable normally
  console.log(curriedSum(1)(2, 3)); // 6, currying of 1st arg
  console.log(curriedSum(1)(2)(3)); // 6, full currying
// 6
// 6
// 6

优化， 采用隐参获取参数
涉及函数参数

//1.手写函数柯里化
function curry(func) {
    const n = func.length;
    let args = Array.prototype.slice.call(arguments).slice(1);
    return function () {
        var _args = args.concat(Array.prototype.slice.call(arguments));
        if (_args.length < n) {
            return curry.call(this, func, ..._args);
        } else {
            return func.apply(this, _args);
        }
    }
  }
  function sum(a, b, c) { 
    return a + b + c;
  }
  let curriedSum = curry(sum);
  console.log(curriedSum(1, 2, 3)); // 6, still callable normally
  console.log(curriedSum(1)(2, 3)); // 6, currying of 1st arg
  console.log(curriedSum(1)(2)(3)); // 6, full currying
// 6
// 6
// 6