How do I remove an array from an array?

Question

Here is my array:

var myarray = [["d1", "sections/Dashboard-summary.html", "Dashboard"], 
               ["add", null, ""],
               ["20", "sections/MW-1-summary.html", "MW-1"],
               ["21", "sections/SB-5-summary.html", "SB-5"]]

How do I remove the second element ["add", null, ""] so that the new array is

[["d1", "sections/Dashboard-summary.html?781", "Dashboard"],
["20", "sections/MW-1-summary.html?903", "MW-1"],
["21", "sections/SB-5-summary.html?539", "SB-5"]]

That element might not always be in the second position but its first value will always be "add". How do I remove the array with the first value (myarray[1][0]) of "add"?

Does this need to be an array? For this kind of thing it would be better to use a linked list. Otherwise you'll have to write code to iterate through your array, find the entry, create a new array 1 size smaller, and copy all the information minus the "add". — Tyler Ferraro
– Tyler Ferraro, Commented Apr 21, 2011 at 1:33
@Matt Yeah you're right. For some reason I completely forgot that fact. Good point. — Tyler Ferraro
– Tyler Ferraro, Commented Apr 21, 2011 at 3:42

Matt Ball · Accepted Answer · 2011-04-21 02:01:25Z

4

That element might not always be in the second position but its first value will always be "add". How do I remove the array with the first value (myarray[1][0]) of "add"?

Use a loop with splice().

for (var i = 0, myarrayLength = myarray.length; i < myarrayLength; i++) {
    if (myarray[i][0] === 'add') {
        myarray.splice(i, 1);
        break;
    }
}

jsFiddle.

edited Apr 21, 2011 at 2:01

Matt Ball

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answered Apr 21, 2011 at 1:30

alex

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3 Comments

Marcelo Over a year ago

slice will return the part of the array that you deleted and will not modify the original array. Splice will actually remove the element from the array.

Marcelo Over a year ago

After commented on your response I realized I made the same mistake :S

Wayne Over a year ago

Note this from the question: "That element might not always be in the second position"

Zach Rattner · Accepted Answer · 2011-04-21 01:32:26Z

0

Use splice, like so:

myarray.splice(1, 1)

See this tutorial for more information on splice.

answered Apr 21, 2011 at 1:32

Zach Rattner

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4 Comments

Matt Ball Over a year ago

Please avoid w3schools. MDC is a much better source for JavaScript reference, in this case see Array.splice().

GravyPlaya Over a year ago

Splice works when you know the position of the element to be removed. But in my case the empty element wont always be in the second position. How do I find the empty element and remove it?

Zach Rattner Over a year ago

You could iterate over the loop and see if typeof(myarray[i]) == "undefined".

Zach Rattner Over a year ago

@Matt Ball: Thanks for the link. I didn't know I was committing such an atrocity.

Marcelo · Accepted Answer · 2011-04-21 01:38:49Z

0

You can remove it completely (slow):

myarray.splice(1, 1);

You can delete it from the array, and left a "hole" in it (left the position 1 undefined):

delete myarray[1];

edited Apr 21, 2011 at 1:38

answered Apr 21, 2011 at 1:33

Marcelo

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