How to identify custom values in an array with javascript?

Question

I have made a survey in which the respondents had a multiple choice question, let's say: "What are your favorite fruits?", they can choose from a list as much as they want, but also they can introduce a custom value in case they want to add a non-listed fruit. The list have the following options: apple, pear, banana, strawberry, and "custom".

I need to make a chart with the info to count how many people chose each fruit. But I will add ALL the custom values in a value called "custom". Let's say I ended up with an array like this one:

[
  {
    "Person": "Person1",
    "Fruits": [ "apple", "banana", "peach" ]
  },
  {
    "Person": "Person2",
    "Fruits": [ "apple", "pear", "strawberry", "coconut" ]
  },
  {
    "Person": "Person3",
    "Fruits": [ "pear", "strawberry" ]
  },
  {
    "Person": "Person4",
    "Fruits": [ "strawberry", "orange" ]
  }
]

To count the already-listed fruits I started using includes(), but IE doesn't support it. So I'm using a code I've found Alternative of .includes() in Internet Explorer.

My Code:
I made a loop for each element in the array and if it includes a certain word it gets stored in its correspondent array:

//I am calling the info with AngularJS don't know if is important to know that
//Declare empty arrays for each fruit
var dataResults = $scope.items, //<---- this is the array with the info, the one I showed before..
    apple = [],
    pear = [],
    banana = [],
    strawberry = [],
    custom = [];

//function to read if an array includes a certain value
function includes(container, value) {
    var returnValue = false;
    var pos = container.indexOf(value);
    if (pos >= 0) {
        returnValue = true;
    }
    return returnValue;
}

//Loop the survey results
for(var i=0; i<dataResults.length; i++) {
    var currentItem = dataResults[i];
    //I push the name of the person if he/she chose apple
    if(includes(currentItem.Fruits, "apple")){
        apple.push(currentItem.Person);
    }
    //I push the name of the person if he/she chose pear
    if(includes(currentItem.Fruits, "pear")){
        pear.push(currentItem.Person);
    }
    //I push the name of the person if he/she chose banana
    if(includes(currentItem.Fruits, "banana")){
        banana.push(currentItem.Person);
    }
    //I push the name of the person if he/she chose strawberry
    if(includes(currentItem.Fruits, "strawberry")){
        strawberry.push(currentItem.Person);
    }
};
//now I wanna see the results in the console for each array
console.log("apple: " + apple.length);
console.log("pear: " + pear.length);
console.log("banana: " + banana.length);
console.log("strawberry: " + strawberry.length);

But now what I don't know is how many people entered a custom value. It doesn't matter what they wrote (because there can be hundreds of different values), but I need to store them all as "custom".
How can I count values that doesn't appear in the list?
Please, Help.

For the recommended polyfill for Array.prototype.includes, see MDN Java Script Reference - includes polyfill — georgeawg
– georgeawg, Commented Apr 28, 2019 at 10:59

Tigger · Accepted Answer · 2019-04-28 06:13:06Z

3

Looks like a good choice for a switch statement to me.

You can also remove the need to use includes().

For example:

//Loop the survey results
var currentItem, f, max;
for(var i=0; i<dataResults.length; i++) {
    currentItem = dataResults[i];
    max = currentItem.Fruits.length;
    for(f=0;f<max;f++) {
        switch(currentItem.Fruits[f]) {
            case "apple" :
                apple.push(currentItem.Person);
                break;
            case "pear" :
                pear.push(currentItem.Person);
                break;
            case "banana" :
                banana.push(currentItem.Person);
                break;
            case "strawberry" :
                strawberry.push(currentItem.Person);
                break;
            default :
                custom.push(currentItem.Person);
        }
    }
}

answered Apr 28, 2019 at 6:13

Tigger

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1 Comment

Soul Eater Over a year ago

don't know why I didn't thought on using switch, it is easier and works perfectly..

Cat · Accepted Answer · 2019-04-28 07:08:00Z

You can check each fruit in the current item to see if it is not on the standard list. If it is not, it must be a custom fruit:

let standardList = ["apple", "pear", "banana", "strawberry"];
for(let fruit of currentItem.Fruits){
  if(!includes(standardList, fruit)){
    custom.push(currentItem.Person);
  }
}

Here is this concept applied in a working snippet:

// Object whose properties are lists, to collect people who like each fruit
var lists = {
  apple: [], pear: [], banana: [], strawberry: [], custom: []
},
// Incoming survey results
dataResults = [
  {"Person": "Person1", "Fruits": ["apple", "banana", "peach"] },
  {"Person": "Person2", "Fruits": ["apple", "pear", "strawberry", "coconut"] },
  {"Person": "Person3", "Fruits": ["pear", "strawberry"] },
  {"Person": "Person4", "Fruits": ["strawberry", "orange"] }
],
// List of standard (non-custom) fruit names
standardList = ["apple", "pear", "banana", "strawberry"];

// Loop through results
for (var i = 0; i < dataResults.length; i++) {
  const currentItem = dataResults[i];
  // Loop though the fruits in the current item
  for (let fruit of currentItem.Fruits) {
    // If fruit is on standard list, push person to a fruit-specific list
    if (standardList.indexOf(fruit) >= 0) { // Uses `indexOf` instead of `includes`
      lists[fruit].push(currentItem.Person);
    }
    // Otherwise, fruit is not on standard list, so push person to "custom" list 
    else {
      //(Assumes no more than one custom fruit per current item)
      lists["custom"].push(currentItem.Person);
    }
  }
};

// For each list in the lists object, print its name and length 
Object.keys(lists).forEach(function(name){
  console.log(`${name}: ${lists[name].length}`);
})

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