function through chain method

Question

Trying to understand chained methods, either like math or cheerio/jQuery, when things get too long I shorten and replace with my own methods.

//这将帮助我在复杂的方法中获得缩短的方法，并应用于项目

function getValue() {  
    this.add = function(y) {
        return x + y;
    };

    this.mult = function(y) {
        return x * y;
    };

    return this;
};

//不使用new操作符的实例会很有趣

const price1 = getValue(8);
const price2 = getValue(2).add(1);
const price3 = getValue(5).add(3).mult(2);

//不重要，但是推进更远：
const price4 = getValue().add(2).add(2);
const price5 = getValue(5).add(2).add(2);

console.log(price1); // 期望值为8
console.log(price2); // 期望值为3
console.log(price3); // 期望值为16
console.log(price4); // 期望值为4
console.log(price5); // 期望值为9

Answer 1

I improved the above code by adding a default value for y to prevent the result from being "nan" when y is not provided. Overall, this is a great answer.

function getValue(x = 0) {
  this.x = x;
  this.add = function(y = 0) {
    this.x += y;
    return this;
  };
  this.mult = function(y = 1) {
    this.x *= y;
    return this;
  };
  this.value = function() {
    return this.x;
  };
  return this;
};

const price1 = getValue(8).value();
const price2 = getValue(2).add(1).value();
const price3 = getValue(5).add(3).mult(2).value();
const price4 = getValue().add(2).add(2).value();
const price5 = getValue(5).add(2).add(2).value();

console.log(price1); // 期望输出 8
console.log(price2); // 期望输出 3
console.log(price3); // 期望输出 16
console.log(price4); // 期望输出 4
console.log(price5); // 期望输出 9

Answer 2

You need to use the getValue function to receive a parameter x. Additionally, your chained functions should return this. Finally, you need a function to unpack the value, i.e. value().

Please note that in price4, you do not pass in the initial value, so it can default to 0.

function getValue(x = 0) {
  this.x = x;
  this.add = function(y) {
    this.x += y;
    return this;
  };
  this.mult = function(y) {
    this.x *= y;
    return this;
  };
  this.value = function() {
    return this.x;
  };
  return this;
};

const price1 = getValue(8).value();
const price2 = getValue(2).add(1).value();
const price3 = getValue(5).add(3).mult(2).value();
const price4 = getValue().add(2).add(2).value();
const price5 = getValue(5).add(2).add(2).value();

console.log(price1); // 期望值为 8
console.log(price2); // 期望值为 3
console.log(price3); // 期望值为 16
console.log(price4); // 期望值为 4
console.log(price5); // 期望值为 9