How to stop a JavaScript for loop

Question

I m using this JavaScript to iterate through an array and find a matching array element   var remSize            szString  remData  remIndex  i   for  i   0  i  lt  remSize length  i                   I m looking for the index i  when the condition is true     remSize i  size    remData size   remIndex   i   remIndex   -1           The array contains these  sizes     34    36    38         remData size is the  size  I m looking for  e g   36     I need to return the index i if the size I m searching for is in the index  Otherwise I need to return -1  Is there a better way to do this

User · Answer

I know this is a bit old  but instead of looping through the array with a for loop  it would be much easier to use the method  lt array gt  indexOf  lt element gt    fromIndex    It loops through an array  finding and returning the first index of a value  If the value is not contained in the array  it returns -1    lt array gt  is the array to look through   lt element gt  is the value you are looking for  and  fromIndex  is the index to start from  defaults to 0    I hope this helps reduce the size of your code

User · Answer

To stop a for loop early in JavaScript  you use break   var remSize            szString      remData      remIndex      i         I assume there s code here putting entries in  remSize  and assigning something to  remData         remIndex   -1     Set a default if we don t find it for  i   0  i  lt  remSize length  i                    I m looking for the index i  when the condition is true      if  remSize i  size     remData size              remIndex   i            break            lt     breaks out of the loop early            If you re in an ES2015  aka ES6  environment  for this specific use case  you can use Array findIndex  to find the entry s index  or Array find  to find the entry itself   both of which can be shimmed polyfilled   var remSize            szString      remData      remIndex         I assume there s code here putting entries in  remSize  and assigning something to  remData         remIndex   remSize findIndex function entry         return entry size     remData size        Array find   var remSize            szString      remData      remEntry         I assume there s code here putting entries in  remSize  and assigning something to  remData         remEntry   remSize find function entry         return entry size     remData size        Array findIndex stops the first time the callback returns a truthy value  returning the index for that call to the callback  it returns -1 if the callback never returns a truthy value  Array find also stops when it finds what you re looking for  but it returns the entry  not its index  or undefined if the callback never returns a truthy value    If you re using an ES5-compatible environment  or an ES5 shim   you can use the new some function on arrays  which calls a callback until the callback returns a truthy value   var remSize               szString        remData        remIndex         I assume there s code here putting entries in  remSize  and assigning something to  remData         remIndex   -1      lt    Set a default if we don t find it remSize some function entry  index          if  entry size     remData size                remIndex   index              return true      lt    Equivalent of break for  Array some                If you re using jQuery  you can use jQuery each to loop through an array  that would look like this   var remSize            szString      remData      remIndex         I assume there s code here putting entries in  remSize  and assigning something to  remData         remIndex   -1      lt    Set a default if we don t find it jQuery each remSize  function index  entry        if  entry size     remData size            remIndex   index          return false      lt    Equivalent of break for jQuery each

User · Answer

The logic is incorrect  It would always return the result of last element in the array   remIndex   -1   for  i   0  i  lt  remSize length  i                if  remSize i  size    remData size            remIndex   i         break

User · Answer

Use for of loop instead which is part of ES2015 release  Unlike forEach  we can use return  break and continue  See https   hacks mozilla org 2015 04 es6-in-depth-iterators-and-the-for-of-loop   let arr    1 2 3 4 5   for  let ele of arr      if  ele  gt  3  break    console log ele

[javascript] How to stop a JavaScript for loop?

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