计算数组中值的出现次数

Question

I have an array as below:

values = [["Cat", true], ["Dog", false], ["Cow", false], ["Owl", true]]

Now I want a code in ReactJS to check how many true are there and how many false .

Someone help me.

Answer 1

Be careful with Truthy & Falsy

 let values = [ ["Cat", true], ["Dog", false], ["Cow", 1], ["Owl", 0], ["donkey", 0] ] let truthy = 0; let nonTruthy = 0; let trueCount = 0; let falseCount = 0; values.forEach(ele => { if (ele[1] === true) trueCount++; if (ele[1] === false) falseCount++; }) values.forEach(ele => { ele[1]? truthy++: nonTruthy++ }) console.log(trueCount, falseCount) // 1 1 console.log(truthy, nonTruthy) // 2 3

Answer 2

This is not a question about react, but about javascript.

One way to go about that is to write a method that counts all occurences.

values.filter(item => item[1] === true).length

This will filter out only items that are TRUE and return the length of this array. Same can be done for filtering false values, or you can subtract true values from the length of the array if you're sure you only have true and false values throughout.

Answer 3

Working example:

 const values = [["Cat", true], ["Dog", false], ["Cow", false], ["Owl", true]];
  let counter = 0;
  values.map((item) => {
    if (item[1]) {
      counter++;
    }
  });
  console.log(counter);

Answer 4

The simplest way to achive it is to use filter

const values = [["Cat", true], ["Dog", false], ["Cow", false], ["Owl", true]];

const trueVals = values.filter(item => item[1]).length;
const falseVals = values - trueVals;

hope it helps!

Answer 5

I am not really familiar with the values array, but if it keeps its formation you can use this:

let filteredArray = values.filter((val) => val[1] === true).length;

Hope I helped!

Answer 6

How about making use of flat() then filtering it out:

 var values = [["Cat", true], ["Dog", false], ["Cow", false], ["Owl", true]] var result = values.flat().filter(k=>k==true).length; console.log(result);