Javascript The prettiest way to compare one value against multiple values

Question

Whats the prettiest way to compare one value against multiples options   I know there are loads of ways of doing this  but I m looking for the neatest   i ask because i d hoped this was workable  it isn t  quite obviously when you look at it    if  foobar     foo  bar             do something

User · Answer

foobar    foo    foobar    bar  otherwise if you are comparing expressions based only on a single integer  enumerated value  or String object you can use switch  See The switch Statement  You can also use the method suggested by Andr   Al  ada Padez  Ultimately what you select will need to depend on the details of what you are doing

User · Answer

What i use to do  is put those multiple values in an array like  var options    foo  bar     and then  use indexOf    if options indexOf foobar   gt  -1        do something     for prettiness   if  foo  bar  indexOf foobar   1        you can t get any more pretty than this        and for the older browsers    https   developer mozilla org en JavaScript Reference Global Objects Array IndexOf    if   Array prototype indexOf        Array prototype indexOf   function  searchElement     fromIndex                 use strict           if  this    null                throw new TypeError                      var t   Object this           var len   t length  gt  gt  gt  0          if  len     0                return -1                    var n   0          if  arguments length  gt  0                n   Number arguments 1                if  n    n       shortcut for verifying if it s NaN                 n   0                else if  n    0  amp  amp  n    Infinity  amp  amp  n    -Infinity                    n    n  gt  0    -1    Math floor Math abs n                                    if  n  gt   len                return -1                    var k   n  gt   0   n   Math max len - Math abs n   0           for    k  lt  len  k                  if  k in t  amp  amp  t k      searchElement                    return k                                  return -1

User · Answer

Since nobody has added the obvious solution yet which works fine for two comparisons  I ll offer it   if  foobar     foo    foobar     bar           do something     And  if you have lots of values  perhaps hundreds or thousands   then I d suggest making a Set as this makes very clean and simple comparison code and it s fast at runtime      pre-construct the Set var tSet   new Set   foo    bar    test1    test2    test3              test the Set at runtime if  tSet has foobar            do something     For pre-ES6  you can get a Set polyfill of which there are many   One is described in this other answer

User · Answer

Why not using indexOf from array like bellow   if   foo  bar  indexOf foobar      -1           do something     Just plain Javascript  no frameworks or libraries but it will not work on IE  lt  9

User · Answer

The switch method  as mentioned by Guffa  works very nicely indeed  However  the default warning settings in most linters will alert you about the use of fall-through  It s one of the main reasons I use switches at all  so I pretty much ignore this warning  but you should be aware that the using the fall-through feature of the switch statement can be tricky  In cases like this  though - I d go for it

User · Answer

I like the pretty form of testing indexOf with an array  but be aware  this doesn t work in all browsers  because Array prototype indexOf is not present in old IExplorers    However  there is a similar way by using jQuery with the   inArray   function    if    inArray field    value1    value2    value3     gt  -1        alert  value     field     is into the list         It could be better  so you should not test if indexOf exists   Be careful with the comparison  don t use    true false   because   inArray returns the index of matching position where the value has been found  and if the index is 0  it would be false when it really exist into the array

User · Answer

Don t try to be too sneaky  especially when it needlessly affects performance  If you really have a whole heap of comparisons to do  just format it nicely   if  foobar     foo        foobar     bar        foobar     baz        foobar     pew           do something

User · Answer

You can use a switch   switch  foobar      case foo    case bar         do something

User · Answer

Just for kicks  since this Q amp A does seem to be about syntax microanalysis  a tiny tiny modification of Andr   Al  ada Padez s suggestion s     and of course accounting for the pre-IE9 shim shiv polyfill he s included   if    foo  bar  indexOf foobar            pretty

[javascript] Javascript: The prettiest way to compare one value against multiple values

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