Meal Maker project error/ undefined.push

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#1

Hi guys I keep getting this error ( /home/ccuser/workspace/learn-javascript-objects-meal-maker/app.js:37
return this._courses[courseName].push(dish);
^
TypeError: Cannot read property ‘push’ of undefined
at Object.addDishToCourse)

I watched the video that was made a few years ago and my syntax is pretty much identical to that…
here is the code:
https://gist.github.com/019ebbfbe3c95ca98e699270eb12f9e7

any help would be great but an explanation as to where i went wrong and why it is wrong would be even more appreciated.

#2

so .push() is an array specific method, calling .push() on undefined gives an error:

undefined.push(1)

So then the next question you should ask yourself is: how/why do I get undefined? When you use a property which does not exists on an object:

console.log({}.nonExisting); // logs: undefined

so then to debug this problem, we would need to log the available properties and the properties which you use:

  addDishToCourse(courseName, dishName, dishPrice) {
    const dish = {
      name: dishName,
      price: dishPrice,
    };
    console.log(Object.keys(this._courses), courseName);
    return this._courses[courseName].push(dish);
  },

I use Object.keys() to get all the available keys/properties, but you could also just log the course object.

#3

Okay thats great and all but I still dont understand because its not undefined, [courseName] would refer to either of these strings ‘appetizers’, ‘mains’, ‘desserts’. So, when I call .push on it, that parameter has already been defined as one of three pramaters once generateRandomMeal(courseName, dishName, dishPrice) is called on the whole function.

#4

Turns out the issue was a typo when calling addDishToCourse() I missed out the s’s on the end of desserts, that makes sense on the debugging now because it will find the miss spelling on desserts

#5

But there is no check if the arguments/values you provide for the courseName parameter of addDishToCourse method is actually one of the three keys/properties of the courses object

Seems you have it resolved.

I partially blame JavaScript here as well, javascript should throw an error when a key/property does not exists on an object. That would make it a lot easier to debug this kind of issue

I suppose, in time we learn to navigate the rough edges of any programming languages.

2 Likes
#6

Thanks For the help though you definitly pushed me in the right direction

1 Like
#7

Hi. I’m stuck at the same point . But i have combed back and forth my code and STILL getting undefined, when trying to push the dish object. I have checked the keys and they exist. but _courses{coursesName) still is undefined.

const menu = {
  _courses: {
    appetizers: [],
    mains: [],
    desserts: []
  },
  get appetizers() {
    return this._courses.appetizers;

  },
  set appetizers(appetizers) {
    this._courses.appetizers = appetizers

  },
  get mains() {
    return this._courses.mains;
  },
  set mains(mains) {
    this._courses.mains = mains
  },
  get desserts() {
    return this._courses.desserts;
  },
  set desserts(desserts) {
    this._courses.desserts = desserts
  }, 
  get courses() {
    return {
      appetizers: this.appetizers,
      mains: this.mains,
      desserts: this.desserts
    }
  },

  addDishToCourse(courseName, dishName, dishPrice){
  const dish = {
    name: dishName,
    price: dishPrice
  };
  console.log(Object.keys(this._courses,courseName))
  return this._courses[courseName].push(dish);
  },
1 Like
#8

where is the rest of your code?

1 Like
#9

Oh, sorry. Here it is.

const menu = {
  _courses: {
    appetizers: [],
    mains: [],
    desserts: []
  },
  get appetizers() {
    return this._courses.appetizers;

  },
  set appetizers(appetizers) {
    this._courses.appetizers = appetizers

  },
  get mains() {
    return this._courses.mains;
  },
  set mains(mains) {
    this._courses.mains = mains
  },
  get desserts() {
    return this._courses.desserts;
  },
  set desserts(desserts) {
    this._courses.desserts = desserts
  }, 
  get courses() {
    return {
      appetizers: this.appetizers,
      mains: this.mains,
      desserts: this.desserts
    }
  },

  addDishToCourse(courseName, dishName, dishPrice){
  const dish = {
    name: dishName,
    price: dishPrice
  };
  console.log(Object.keys(this._courses,courseName))
  return this._courses["courseName"].push(dish)
  },

  getRandomDishFromCourse(courseName) {
    let dishes = this._courses[courseName];
    const randomIndex = Math.random(Math.floor() * dishes.length)
    return dishes[randomIndex];
  },

  generateRandomMeal() {
    let appetizer = getRandomDishFromCourse("appetizers");
    let mains = getRandomDishFromCourse("mains");
    let desserts = getRandomDishFromCourse("desserts");
  }
}

menu.addDishToCourse("main","wings", 4.50)
```
#10

exactly the same problem? except you have 'main' instead of 'mains', but you should be able to debug that with the same steps I provided for OP?

2 Likes
#11

You are right.

I thought that courseName parameter was a variable that was going to be added to the menu object. But it actually points to the object keys .

Thank you !!