Checking values in a javascript array

Question

I have simple JavaScript question.

I have an array (xyz) of 9 objects (Cell), each with 2 properties (e,v).

Is there any easy way to check if all the values of one of the properties are false?

Something like:

var myArray = xyz[];

if(all myArray.e==false){
    do this;
}

---

Thanks :D

Array[9]
0:Cell
 e:false
 v:"x"
1:Cell
2:Cell
3:Cell
4:Cell
...etc

Answer 1

You can use JavaScript Array every() Method

var myArray = [xyz];
if (myArray.every(obj => !obj.e)) {
   do this;
}

Answer 2

You could do this with the reduce function.

Try:

const areAllFalse = !myArray.reduce((prev, cur) => prev || cur, false)

Check out the MDN docs for reduce for more info on how it works.

Answer 3

You should do

let areAllFalse = true;
for (let obj in myArray){
    if (e.v) {
       areAllFalse = false;
       break;
    }
}
if (areAllFalse){
    // Do stuff
}

Basically:

• You instantiate a variable (in this snippet is called areAllFalse ) to true (you are assuming that all the elements will be false)
• Then you cycle them all
• If at least one is true, you change the value of that variable and exit from the cycle as it's useles to continue
• If the variable areAllFalse is true, every element in the array is false, so you can execute your code

This will work in every programming language (with the obvious syntax changes)

I hope I helped you :)

Answer 4

There's a few different ways you could approach this. One way would be by using every . ( MDN Docs )

function myTest(thisItem) {
    return !thisItem.e;
}

var myArray = [
    {e: false, v: 111},
    {e: false, v: 222},
    {e: false, v: 333}
];

var output = myArray.every(myTest);

console.log(output);
// expected output: true

Answer 5

You can use array#every with to check for your condition to be true for all the objects in your array. Use Object#keys to iterate over keys in an object and check for false value using array#some .

 var arr = [{e:false, v:'x'}, {e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'}], result = arr.every(o => Object.keys(o).some(k => !o[k])); console.log(result); 

To check for e property in your object, you should first check if e key exists in the object then check if its value is false.

 var arr = [{e:false, v:'x'}, {e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'},{e:false, v:'x'}], result = arr.every(o => 'e' in o && !oe); console.log(result); 

Answer 6

You have multiple options to do that, like

1. Normal for loop
2. ForEach loop
3. Or any looping mechanism using that you can check whether it contains a false property.

But for short answer I think you can use findIndex that will return index if it matches condition: Example :

if(xyz.findIndex(k => k.e== false) > -1){
console.log("it contains false value also");
}