Jquery each - Stop loop and return object

问题

Can anybody tell me why the loop did not stop after the 5 entry?

http://jsbin.com/ucuqot/edit#preview

$(document).ready(function()
{
  someArray = new Array();
  someArray[0] = \'t5\';
  someArray[1] = \'z12\';
  someArray[2] = \'b88\';
  someArray[3] = \'s55\';
  someArray[4] = \'e51\';
  someArray[5] = \'o322\';
  someArray[6] = \'i22\';
  someArray[7] = \'k954\';  

  var test =  findXX(\'o322\');   

});

function findXX(word)
{  
  $.each(someArray, function(i)
  {
    $(\'body\').append(\'-> \'+i+\'<br />\');
    if(someArray[i] == \'someArray\')
    {
      return someArray[i]; //<--- did not stop the loop!
    }   
  });  
}

回答1:

Because when you use a return statement inside an each loop, a "non-false" value will act as a continue, whereas false will act as a break. You will need to return false from the each function. Something like this:

function findXX(word) {
    var toReturn; 
    $.each(someArray, function(i) {
        $('body').append('-> '+i+'<br />');
        if(someArray[i] == word) {
            toReturn = someArray[i];
            return false;
        }   
    }); 
    return toReturn; 
}

From the docs:

We can break the $.each() loop at a particular iteration by making the callback function return false. Returning non-false is the same as a continue statement in a for loop; it will skip immediately to the next iteration.

回答2:

here :

http://jsbin.com/ucuqot/3/edit

function findXX(word)
{  
  $.each(someArray, function(i,n)
  {
    $('body').append('-> '+i+'<br />');
    if(n == word)
    {
      return false;
    }   
  });  
}

回答3:

modified $.each function

$.fn.eachReturn = function(arr, callback) {
   var result = null;
   $.each(arr, function(index, value){
       var test = callback(index, value);
       if (test) {
           result = test;
           return false;
       }
   });
   return result ;
}

it will break loop on non-false/non-empty result and return it back, so in your case it would be

return $.eachReturn(someArray, function(i){
    ...

回答4:

Try this ...

  someArray = new Array();
  someArray[0] = 't5';
  someArray[1] = 'z12';
  someArray[2] = 'b88';
  someArray[3] = 's55';
  someArray[4] = 'e51';
  someArray[5] = 'o322';
  someArray[6] = 'i22';
  someArray[7] = 'k954';  

  var test =  findXX('o322'); 
  console.log(test);



function findXX(word)
{  
  for(var i in someArray){


    if(someArray[i] == word)
    {
      return someArray[i]; //<---  stop the loop!
    }   
  }
}

回答5:

"We can break the $.each() loop at a particular iteration by making the callback function return false. Returning non-false is the same as a continue statement in a for loop; it will skip immediately to the next iteration."

from http://api.jquery.com/jquery.each/

Yea, this is old BUT, JUST to answer the question, this can be a bit simpler:

function findXX(word) {
  $.each(someArray, function(index, value) {
    $('body').append('-> ' + index + ":" + value + '<br />');
    return !(value == word);
  });
}
$(function() {
  someArray = new Array();
  someArray[0] = 't5';
  someArray[1] = 'z12';
  someArray[2] = 'b88';
  someArray[3] = 's55';
  someArray[4] = 'e51';
  someArray[5] = 'o322';
  someArray[6] = 'i22';
  someArray[7] = 'k954';
  findXX('o322');
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

A bit more with comments:

function findXX(myA, word) {
  let br = '<br />';//create once
  let myHolder = $("<div />");//get a holder to not hit DOM a lot
  let found = false;//default return
  $.each(myA, function(index, value) {
    found = (value == word);
    myHolder.append('-> ' + index + ":" + value + br);
    return !found;
  });
  $('body').append(myHolder.html());// hit DOM once
  return found;
}
$(function() {
  // no horrid global array, easier array setup;
  let someArray = ['t5', 'z12', 'b88', 's55', 'e51', 'o322', 'i22', 'k954'];
  // pass the array and the value we want to find, return back a value
  let test = findXX(someArray, 'o322');
  $('body').append("<div>Found:" + test + "</div>");
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

NOTE: array .includes() may better suit here https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes

Or just .find() to get that https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find

来源：https://stackoverflow.com/questions/8224375/jquery-each-stop-loop-and-return-object

标签

jquery

loops

return

each