deleting a specific object in a javascript array

Question

im doing a test on deleting objects inside an array... since this is a test, this is rather an informal code..

<script type="text/javascript">

// initialize array and objects
var fruits = new Array();

var z = {
  test1: "test0",
  test2: "test2"
}

fruits.push(z);
var z2 = {
  test1: "test1",
  test2: "test2"
}
fruits.push(z2);
var z3 = {
  test1: "test2",
  test2: "test2"
}
fruits.push(z3);
var z4 = {
  test1: "test3",
  test2: "test2"
}
fruits.push(z4);
var z5 = {
  test1: "test4",
  test2: "test2"
}
fruits.push(z5);

// display array length
document.write("array length is " + fruits.length + "<br>");

// traverse array
for(var x = 0; x < fruits.length; x++){

  // display object content in array
  document.write(fruits[x].test1 + " ");

  // delete object in array where variable test1 is equal to "test2"
  if(fruits[x].test1 == "test2"){
    fruits.splice(x, 1);
    //document.write("array length is " + fruits.length + "<br>");
  }
}
</script>

now this code works fine (deleting an object on the array) but it deletes the one after the one i want deleted (in the code above, i want to delete the object in index 2, but it deletes the object in index 3)

anything i'm doing wrong in this code?

TIA :)

jon · Accepted Answer · 2011-09-02 08:56:21Z

6

You should never try to alter an array while iterating it. Instead, save the index of the element you want to delete in a variable, and remove it after the for loop.

answered Sep 2, 2011 at 8:56

jon

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Comments

mahulst · Accepted Answer · 2011-09-02 08:49:10Z

This should work:

<script type="text/javascript">

    // initialize array and objects
    var fruits = new Array();

    var z = {
      test1: "test0",
      test2: "test2"
    }

    fruits.push(z);
    var z2 = {
      test1: "test1",
      test2: "test2"
    }
    fruits.push(z2);
    var z3 = {
      test1: "test2",
      test2: "test2"
    }
    fruits.push(z3);
    var z4 = {
      test1: "test3",
      test2: "test2"
    }
    fruits.push(z4);
    var z5 = {
      test1: "test4",
      test2: "test2"
    }
    fruits.push(z5);

    // display array length
    document.write("array length is " + fruits.length + "<br>");

    // traverse array
    for(var x = 0; x < fruits.length; x++){

      // display object content in array
      document.write(fruits[x].test1 + " ");

      // delete object in array where variable test1 is equal to "test2"
      if(fruits[x].test1 == "test2"){
        fruits.splice(x-1, 1);
        //document.write("array length is " + fruits.length + "<br>");
      }
    }
    </script>

thanks for your answer mike :) unfortunately, i tried that workaround awhile ago but it still didn't did the job... do you have other ideas? thanks again :)

Adrian Heine · Accepted Answer · 2011-09-02 09:13:03Z

0

Use ''filter'' as implemented in underscore.js:

_.filter(fruits, function (fruit) {
    return fruit.test1 !== "test2";
});

This has the advantage of using a fast, native JavaScript method (''filter'') where available.

answered Sep 2, 2011 at 9:13

Adrian Heine

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1 Comment

jason Over a year ago

thanks for your response Adrian, i'll also try this workaround :)

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