Check If Each Item In An Array Is Identical In Javascript

I need to test whether each item in an array is identical to each other. For example: var list = ['l','r','b'] Should evaluate as false, because each item is not identical. On the

Solution 1:

functionidentical(array) {
    for(var i = 0; i < array.length - 1; i++) {
        if(array[i] !== array[i+1]) {
            returnfalse;
        }
    }
    returntrue;
}

Solution 2:

In ES5, you could do:

arr.every(function(v, i, a) {
   // first item: nothing to compare with (and, single element arrays should return true)// otherwise:  compare current value to previous valuereturn i === 0 || v === a[i - 1];
});

.every does short-circuit as well.

Solution 3:

You could always do a new Set, and check the length.

var set1 = [...newSet(list)].length === 1;

Solution 4:

The one line answer is:

arr.every((val, ind, arr) => val === arr[0]);

You can look into Array.every for more details.

Note:

1. Array.every is available ES5 onwards.
2. This method returns true for any condition put on an empty array.
3. Syntax: arr.every(callback[, thisArg]) or array.every(function(currentValue, index, arr), thisValue)
4. It does not change the original array
5. The execution of every() is short-circuited. As soon as every() finds an array element that doesn't match the predicate, it immediately returns false and doesn't iterate over the remaining elements

Solution 5:

functionmatchList(list) {
  var listItem = list[0];

  for (index in list) {
    if(list[index] != listItem {
       returnfalse;
    }
  }

  returntrue;
}