javascript check if the values of an array are present as a key in an object

Question

I need to detect if the values of an array are present in an object as a key

I tried this way

var color = {
             1: "Red",
             2: "Blue",
             3: "Yellow",
             4: "Violet",
             5: "Green",
             7: "Orange"
            };

var myColor = [3, 1];

for(const [key, value] of Object.entries(color)){

    var bgIco = (myColor.includes(key)) ? '[' + key + ']' + value + ' - Yes' : '[' + key + ']' + value + ' - No';

    console.log(bgIco);

}

But it always comes back no

If in the includes function I manually put a number in the object instead of the key variable then it works, what am I doing wrong?

CertainPerformance · Accepted Answer · 2021-04-13 16:47:00Z

1

Object properties are always strings (or symbols), even if they look like numbers when declaring them:

const obj = { 1: 'foo' };

const key = Object.keys(obj)[0];
console.log(key === 1);
console.log(typeof key);

So, map the myColor array to strings first:

var myColor = [3, 1].map(String);

Otherwise, the includes check will fail (since includes requires === - or SameValueZero - for a match to be found)

answered Apr 13, 2021 at 16:47

CertainPerformance

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1 Comment

Robert Over a year ago

Thanks a lot, it works perfectly, I knew it was something there, but I couldn't figure out what

charlietfl · Accepted Answer · 2021-04-13 16:52:40Z

0

If you want to check the array against the object seems simpler to iterate the array instead

var color = {
             1: "Red",
             2: "Blue",
             3: "Yellow",
             4: "Violet",
             5: "Green",
             7: "Orange"
            };

var myColor = [3, 1, 55];

for(let k of myColor){
   console.log(k, color.hasOwnProperty(k), /* OR */  k in color);      
}

answered Apr 13, 2021 at 16:52

charlietfl

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