Javascript-从数组中删除元素/对某个值以上的数组中的元素求和

Question

(1)

I have here an array that is a mix of strings and ints:

var newArr = [ 22, 7, "2761", 16, "91981", "37728", "13909", "247214", "8804", 6, 2 ]

My ultimate goal is to remove the values that are ints, and add the other values.

One way I tried to achieve this was to first convert all to ints:

  for (element in newArr) {
    newArr[element] = parseInt(newArr[element], 10);
  }

Is this the best way to do that? It seems to output an array of ints like this:

var newArr = [ 22, 7, 2761, 16, 91981, 37728, 13909, 247214, 8804, 6, 2 ];

(2)

Then I would like to only sum elements in newArr that are above the value of 30. This is my code:

var newArr = [ 22, 7, 2761, 16, 91981, 37728, 13909, 247214, 8804, 6, 2 ];

  for (element in newArr) {
    if (newArr[element] > 30) {
      sum += newArr[element];
    }
  }

It doesn't seem to be working. Please help.

(3) A final question is:

How could I just eliminate the ints from newArr in step (1), as this would negate the need for the other code, I guess.

A simple solution using only javascript syntax (no jquery) would be appreciated. (unless the overwhelming consensus is that jquery would be a better option) Thanks Javascript Ninjas!

Answer 1

First, you might want to look into Array.map . This will allow you to convert them all to ints.

var result = newArr.map(function(x) {
  return parseInt(x, 10);
});

Then you can use Array.filter to remove any elements less than or equal to 30.

result = result.filter(function(x) {
  return x > 30;
});

Finally, you can use Array.reduce to sum them all together.

sum = result.reduce(function(sum, x) {
  return sum + x;
}, 0);

There are numerous ways of accomplishing this but I like this approach because you can chain it together.

var sum = newArray.map(function(x) {
      return parseInt(x, 10);
    })
    .filter(function(x) {
      return x > 30;
    })
    .reduce(function(sum, x) {
      return sum + x;
    }, 0);

Answer 2

Detect the type then remove them: Here I go through the array, then remove the numbers then go through it again:

var newArr = [22, 7, "2761", 16, "91981", "37728", "13909", "247214", "8804", 6, 2];

for (element in newArr) {
    alert(typeof newArr[element] + ":" + newArr[element]);
}
for (var i = newArr.length; i--;) {
    if (typeof newArr[i] === "number") {
        newArr.splice(i, 1);
    }
}
alert(newArr.length);
for (element in newArr) {
    alert(typeof newArr[element] + ":" + newArr[element]);
}

Answer 3

I think the best approach to do all this in single iteration would be .

1. Checking each element with typeof item!="number"

2. Using Array's Reduce Right : Sample Use:

   [0, 1, 2, 3, 4].reduceRight(function(previousValue, currentValue, index, array) { return previousValue + currentValue; });

You can check the previousValue and currentValue with typeof and return the addition if parseInt() return's 30 or more.