从数组获取值-Javascript

Question

Trying my best, but still not able to log the result at the end.

var arr = [2, 2, 2, 2, 2, 4, 5, 5, 5, 9];

function foo(arr) {
    var a = [], b = [], prev;

    arr.sort();
    for ( var i = 0; i < arr.length; i++ ) {
        if ( arr[i] !== prev ) {
            a.push(arr[i]);
            b.push(1);
        } else {
            b[b.length-1]++;
        }
        prev = arr[i];
    }

    return [a, b];
}

var result = foo(arr);
var a = result[0]
var b = result[1]
var aa=a.split(",");
var ab=b.split(",");
var a = a.split(",").length;
var b = b.split(",").length;
for (c = 0; c < a; c++){
console.log(aa[c]);
console.log(ab[c]);}

I want to get values from two array result[0] and result[1] one by one in the loop.
Right now I am able to get all the values comma separated but when I split values, nothing shows up.

Answer 1

You can create an empty object to track the number of repetitions & an array to hold only unique values.Use indexOf to find if element already exist in uniqArray .

 var arr = [2, 2, 2, 2, 2, 4, 5, 5, 5, 9]; var repCount = {}, // to track number of repetitions uniqArray = []; // holds only unique values arr.forEach(function(item) { if (uniqArray.indexOf(item) == -1) { // id item is not present push it uniqArray.push(item) } // check if the object already have a key for example 2,4,5,9 if (!repCount.hasOwnProperty(item)) { repCount[item] = 1 // if not then create new key } else { // if it is there then increase the count repCount[item] = repCount[item] + 1 } }) console.log(uniqArray, repCount) 

Answer 2

Looking at your comment...

So basically i want to get the unique no. from array and the no. of repetition of that particular value into another variable

You can achieve this by using reduce function

 var arr = [2, 2, 2, 2, 2, 4, 5, 5, 5, 9]; var a = arr.reduce(function (acc, next) { acc[next] = acc[next] ? acc[next] + 1 : 1; return acc; }, {}); console.log(a); 

which gives you a hash with unique numbers as keys and their counts as values. From here you can easily break it into two arrays if you really need to..

Answer 3

You were almost there:

  var arr = [2, 2, 2, 2, 2, 4, 5, 5, 5, 9]; function foo(arr) { var a = [], b = [], prev; arr.sort(); for ( var i = 0; i < arr.length; i++ ) { if ( arr[i] !== prev ) { a.push(arr[i]); b.push(1); } else { b[b.length-1]++; } prev = arr[i]; } return [a, b]; } var result = foo(arr); var a = result[0] var b = result[1] for (i=0; i<a.length; i++){ console.log("Number: " + a[i] + "; Time repeated:"+ b[i]); }