CODEWITHSUNDEEP
javascript
jstone
jstone

Reputation: 445

Push to an Array using a for loop

im a JS newbie. Trying to figure out this problem below. I am stuck on the "if" statement and not sure exactly what to put in. Also im not sure if my "push" is setup right 

// Define a function named `compact` that accepts an array and returns
// another array with all the falsey values removed from it. For example,
// if this array was passed in:
//   [1, 4, 0, '', undefined, false, true, null, {mj: 'mj'}, 'Hello']
// the function would return this, as a result:
//   [1, 4, true, {mj: 'mj'}, 'Hello']

var compact = function (array) {
    var truthyValues = [];
    for (var i = 0; i < array.length; i += 1) {
        if () {
            truthyValues.push[i];
        }
    }
    return truthyValues;
};

Upvotes: 4

Views: 653

Answers (4)

Jed Schneider
Jed Schneider

Reputation: 14671

if (typeof array[i] !== "undefined" && array[i] !== null) {// push to array // }

most of these other answers will not work for falsy and existy values. You'll need to define what you intend to be existy and write a helper function for that. you could use the one I provided as a start and then roll your own.

Upvotes: 1

scrblnrd3
scrblnrd3

Reputation: 7416

Just put the value you want to check is truthy in the if statement, since the if statement checks for truthiness.

if(array[i]){
  truthyValues.push(array[i]);
}

Upvotes: 4

C1pher
C1pher

Reputation: 1972

I think you can just use:

if (array[i]) { truthyValues.push(array[i]); }

Values like null will trigger false.

Upvotes: 1

Scott Mermelstein
Scott Mermelstein

Reputation: 15397

You're close. Here's what the if should be:

if (array[i]) {
    truthyValues.push(array[i]);
}

Since you want to check for truthiness of each array element, just put array[i] in the if block. That gets the value of the array at i, and will evaluate as true if that value is truthy.

Then push not i - the index into array - but array[i], so that the actual value is in truthyValues.

Upvotes: 4

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