Check for false

Question

Is there any better way of doing this   if borrar       false        alert  tatatata bum bum bum prapra      return false

User · Answer

If you want it to check explicit for it to not be false (boolean value) you have to use

if(borrar() !== false)

But in JavaScript we usually use falsy and truthy and you could use

if(!borrar())

but then values 0, '', null, undefined, null and NaN would not generate the alert.

The following values are always falsy:

false,
,0 (zero)
,'' or "" (empty string)
,null
,undefined
,NaN

Everything else is truthy. That includes:

'0' (a string containing a single zero)
,'false' (a string containing the text “false”)
,[] (an empty array)
,{} (an empty object)
,function(){} (an “empty” function)

Source: https://www.sitepoint.com/javascript-truthy-falsy/

As an extra perk to convert any value to true or false (boolean type), use double exclamation mark:

!![] === true
!!'false' === true
!!false === false
!!undefined === false

User · Answer

If you want to check for false and alert if not  then no there isn t  If you use if val   then anything that evaluates to  truthy   like a non-empty string  will also pass  So it depends on how stringent your criterion is  Using     and     is generally considered good practice  to avoid accidentally matching truthy or falsy conditions via JavaScript s implicit boolean tests

User · Answer

If you want an explicit check against false  and not undefined  null and others which I assume as you are using     instead of     then yes  you have to use that  Also  this is the same in a slightly smaller footprint  if borrar        1

User · Answer

You can use something simpler  if  var       console log  var is false

User · Answer

Like this  if borrar            Do something    If borrar   returns true then do something  if it is not false

User · Answer

Checking if something isn t false    So it s true  just if you re doing something that is quantum physics  if   borrar       false    or if borrar       true

[javascript] Check for false

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