what is Array any for javascript

Question

I m looking for a method for javascript returns true or false when it s empty   something like Ruby any  or empty      any     gt  false    empty     gt  true

User · Answer

polyfill    Array prototype any function        return  this some  this some    arguments  this filter    arguments  reduce  a b   gt  a    b      If you want to call it as Ruby   that it means  any not  any    use   Object defineProperty  Array prototype   any       get  function       return  this some  this some function e  return e   this filter function e  return e   reduce  a b   gt  a    b                   https   en wikipedia org wiki Polyfill

User · Answer

JavaScript arrays can be  empty   in a sense  even if the length of the array is non-zero   For example   var empty   new Array 10   var howMany   empty reduce function count  e    return count   1     0     The variable  howMany  will be set to 0  even though the array was initialized to have a length of 10   Thus because many of the Array iteration functions only pay attention to elements of the array that have actually been assigned values  you can use something like this call to  some   to see if an array has anything actually in it   var hasSome   empty some function e    return true        The callback passed to  some   will return true whenever it s called  so if the iteration mechanism finds an element of the array that s worthy of inspection  the result will be true

User · Answer

Just use Array length   var arr        if  arr length     console log  not empty    else    console log  empty      See MDN

User · Answer

var a       a length  gt  0   I would just check the length  You could potentially wrap it in a helper method if you like

User · Answer

Array has a length property       length    0  0  length    1  4  8  15  16  23  42  length    6

User · Answer

The JavaScript native  some   method does exactly what you re looking for   function isBiggerThan10 element  index  array      return element  gt  10      2  5  8  1  4  some isBiggerThan10       false  12  5  8  1  4  some isBiggerThan10      true

User · Answer

JavaScript has the Array prototype some   method    1  2  3  some  num    gt  num   2     0       returns true because there s  at least  one even number in the array   In general  the Array class in JavaScript s standard library is quite poor compared to Ruby s Enumerable  There s no isEmpty method and  some   requires that you pass in a function or you ll get an undefined is not a function error  You can define your own  isEmpty   as well as a  any   that is closer to Ruby s like this   Array prototype isEmpty   function         return this length     0     Array prototype any   function func       return this some func    function x    return x         Libraries like underscore js and lodash provide helper methods like these  if you re used to Ruby s collection methods  it might make sense to include them in your project

User · Answer

What you want is  empty not  empty   to fully  mimics Ruby           Object defineProperty  Array prototype   empty                get  function       return this length   0                    then     empty   true  3 2 8  empty   false     For any   see my answer here

User · Answer

I believe this to be the cleanest and readable option  var empty       empty some x   gt  x     returns false

User · Answer

If you really want to got nuts  add a new method to the prototype   if     empty  in Array prototype       Array prototype empty   function          return this length     0           1  2  empty      false    empty      true   DEMO

User · Answer

I m a little late to the party  but        some x   gt    x

[javascript] what is Array.any? for javascript

polyfill* :

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