Using if statement to filter data with multiple string values

Question

Using If statement to filter data with multiple string values

i want to sort the file extension in one line because if i dont do that i have to write multiple lines of code which i think is a waste of time. can i get some help here

if (fileExtension === "jpg"||"Jpeg"||"png"||"svg"){
//do something 
}
else{
//do something else
}

if have so file extension jpg then its directly switching to else statement and if i give just jpg i.e if (fileExtension === "jpg") then the code runs fine i want to use multiple.

Possible duplicate of [Javascript: The prettiest way to compare one value against multiple values](https://stackoverflow.com/questions/9121395/javascript-the-prettiest-way-to-compare-one-value-against-multiple-values) — Ivar, Apr 15 '19 at 11:49
`if (["jpg","jpeg","png","svg"].includes(fileExtension.toLowerCase()))` Did you try searching before asking? there are tons of questions like this, having tons of **great** answers to check. — briosheje, Apr 15 '19 at 11:49
You can use `.indexOf()` like `if(["jpg","jpeg","png","svg"].indexOf(fileExtension) > -1)` — Mamdouh Saeed, Apr 15 '19 at 11:53

Maheer Ali · Answer 1 · 2019-04-15T12:12:10.770

"jpg"||"Jpeg"||"png"||"svg" is an expression which will evaluate to first truthy value. Here "jpg" is first truthy value so while whole expression becomes "jpg". See Short-circuit evaluation .

You can store all the values in array and then use some() on array and compare it with fileExtension

"Jpeg" may cause some problem. capital J. I would suggest you to change all the values to lower case and then compare inside some()

let fileExtension = "svg"

if (["jpg","jpeg","png","svg"].some(x => fileExtension.toLowerCase() === x)){
  console.log("found")
}
else{
  cosnole.log("not found")
}

Note: You can also use includes() in this case. But I would prefer some() because it allows user to compare with multiple conditions

Well done for explaining why the code didn't work. As a side note, I would check for lowercase / uppercase values as an extra feature, since the issue likely would happen with "Jpeg". — briosheje, Apr 15 '19 at 11:52

Andy · Answer 2 · 2019-04-15T12:10:07.083

3

Everyone else is using an array, so here's an example with a regex [1] [2] instead:

function testExtension(fileExtension) {
  if (/jpg|jpeg|png|svg/.test(fileExtension.toLowerCase())) {
    console.log(`${fileExtension} found`);
  } else {
    console.log(`${fileExtension} not found`); 
  }
}

testExtension('mpg');
testExtension('jpg');
testExtension('svg');

edited Apr 15 '19 at 12:10

answered Apr 15 '19 at 11:54

Andy

61,948
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score 0 · Answer 3 · answered Apr 15 '19 at 11:49

0

if (fileExtension === "jpg"|| fileExtension ==="Jpeg" || fileExtension ==="png" || fileExtension ==="svg"){
//do something 
}
else{
//do something else
}

you should check each string with the fileExtension.

answered Apr 15 '19 at 11:49

Mohammed Rabiulla RABI

473
8
26

I would use `.some` instead of writing a novel ;) – iLuvLogix Apr 15 '19 at 11:51
i too but i thought to explain as simple way for new contributor – Mohammed Rabiulla RABI Apr 15 '19 at 11:52
Though your answer solves the issue, I would recommend (even to a new contributor) to show how the problem is solved by providing 'best-practice'- examples/solutions ;) – iLuvLogix Apr 15 '19 at 11:56
so if he/she may be beginner that will go bounce above the head – Mohammed Rabiulla RABI Apr 15 '19 at 11:58
Good point - but don't wrongly assume that just because someone is new on SO this person is not familiar to using functions instead of statements/declarations ;) – iLuvLogix Apr 15 '19 at 12:02
every one has different thoughts what i feel right i have done. – Mohammed Rabiulla RABI Apr 15 '19 at 12:03

score 0 · Answer 4 · answered Apr 15 '19 at 11:50

0

Includes can solve your problem.

if (["jpg", "Jpeg", "png", "svg"].includes(fileExtension)) {
   //do something 
} else{
   //do something else
}

answered Apr 15 '19 at 11:50

Remi Sture

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5
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Beri · Answer 5 · 2019-04-15T11:55:02.183

You could use includes prototype of Array:

if (['jpg', 'Jpeg', 'png', 'svg'].includes(fileExtension)) {
    ...
}

You can also add toLowerCase(), to be a bit safer:

if (['jpg', 'jpeg', 'png', 'svg'].includes(fileExtension.toLowerCase())) {
    ...
}

As an alternative (but much less readable) series of OR conditions:

if (fileExtension === 'jpg' || fileExtension === 'Jpeg' 
    || fileExtension === 'png' || fileExtension ==='svg'){

as you can see it will be less readable, with more arguments.

Mamdouh Saeed · Answer 6 · 2019-04-15T12:07:44.410

0

Using .indexOf() which returns the item position, if the item doesn't exist it returns -1

if(["jpg","jpeg","png","svg"].indexOf(fileExtension) > -1){
//do something...
}

Another way Using .filter()

if(["jpg","jpeg","png","Svg"].filter(function(i){return i.toLowerCase() === fileExtension.toLowerCase()}).length == 1){
    //do something...
    }

edited Apr 15 '19 at 12:07

answered Apr 15 '19 at 11:59

Mamdouh Saeed

2,302
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Using if statement to filter data with multiple string values

6 Answers6