Javascript loop an array to find numbers divisible

问题:

I am needing to find the correct way to have javascript loop through an array, find all numbers that are divisible by 3, and push those numbers into a new array.

Here is what I have so far..

var array = [],
    threes = [];

function loveTheThrees(array) {
    for (i = 0, len = array.length; i < len; i++) {
    threes = array.push(i % 3);
  }
  return threes;
}

So if we pass through an array of [1, 2, 3, 4, 5, 6] through the function, it would push out the numbers 3 and 6 into the "threes" array. Hopefully this makes sense.

回答1:

You can use Array#filter for this task.

filter() calls a provided callback function once for each element in an array, and constructs a new array of all the values for which callback returns a true value or a value that coerces to true. callback is invoked only for indexes of the array which have assigned values; it is not invoked for indexes which have been deleted or which have never been assigned values. Array elements which do not pass the callback test are simply skipped, and are not included in the new array.

function loveTheThrees(array) {
    return array.filter(function (a) {
        return !(a % 3);
    });
}
document.write('<pre>' + JSON.stringify(loveTheThrees([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]), 0, 4) + '</pre>');

回答2:

var array = [],
three = [];

function loveTheThrees(array) {
for (i = 0, len = array.length; i < len; i++) {
    if(array[i] % 3 == 0){
        three.push(array[i]);
     }
   }
 }

回答3:

console.log([1, 2, 3, 4, 5, 6, 7].filter(function(a){return a%3===0;}));

Array.filter() iterates over array and move current object to another array if callback returns true. In this case I have written a callback which returns true if it is divisible by three so only those items will be added to different array

回答4:

Using Filter like suggested by Nina is defiantly the better way to do this. However Im assuming you are a beginner and may not understand callbacks yet, In this case this function will work:

function loveTheThrees(collection){
        var newArray = []
        for (var i =0; i< collection.length;i++){
            if (myArray[i] % 3 === 0){
                newArray.push(collection[i])
            }
        }
        return newArray;
    }

回答5:

loveTheThrees=(arr)=>arr.filter(el=>Boolean(parseFloat(el)) && isFinite(el) && !Boolean(el%3))

es6 version + skipping non numbers

loveTheThrees([null,undefined,'haha',100,3,6])

Result: [3,6]

回答6:

Check if the number is divisible by 3 if so then add it to array. Try this

function loveTheThrees(array) {
    for (i = 0, len = array.length; i < len; i++) {
      if(array[i] % 3 == 0){
        three.push(array[I]);
     }
  }

回答7:

var originalArray = [1, 2, 3, 4, 5, 6, 7, 8, 9];
function loveTheThrees(array1) {
  var threes = [];
  for (var i = 0; i < array1.length; i++) {
    if (array1[i] % 3 === 0) {
      threes.push(array1[i]);
    }
  }
  return threes;
}
loveTheThrees(originalArray);

回答8:

In ES6:

const arr = [1, 33, 54, 30, 11, 203, 323, 100, 9];

// This single line function allow you to do it:
const isDivisibleBy3 = arr => arr.filter(val => val % 3 == 0);


console.log(isDivisibleBy3(arr));
// The console output is [ 33, 54, 30, 9 ]