removing strings from array with conditions

Question

I'm trying to write function in javascript for removing strings from array. Array is dynamically created and from time to time I add new strings to it. When I remove strings from it I first check if string is really in it.

I have one additional condition. If string that is gonna be removed is equal for example to 'bicycle' than I want to also check for 'motorbike' and if it exists remove it also. And if string given is 'motorbike' I want to remove possible occurences of 'bicycle'.

So far I have something like this:

options_array = []

function remove_option(option) {
  var option_index = options_array.indexOf(option);
  if(option_index != -1)
    options_array.splice(option_index, 1);
  if(option == 'bicycle') {
    option_index = options_array.indexOf('motorbike');
    if(option_index != -1)
      options_array.splice(option_index, 1);
  } else if(option == 'motorbike') {
    option_index = options_array.indexOf('bicycle');
    if(option_index != -1)
      options_array.splice(option_index, 1);
  }
}

It works but is it possible to make it nicer and more DRY?

jQuery =/= javascript. jQuery is a library programmed in javascript to do various things easier. — h2ooooooo
– h2ooooooo, Commented Oct 8, 2013 at 13:41
This is messy, say you have another thing like 'tricycle' that you also want to remove, the code will get very laborious. Think about the structure of the objects instead. Have an array of objects and each object can have a parent type. You can then search for all objects of the same parent type and delete them all (if that is what is required) — mbx-mbx
– mbx-mbx, Commented Oct 8, 2013 at 13:44
Instead of options_array.indexOf you can use $.inArray("item",options_array) for all browser compatibility. — sudhansu63
– sudhansu63, Commented Oct 8, 2013 at 13:45

laconbass · Accepted Answer · 2013-10-08 14:25:51Z

1

See Array.prototype.filter reference on mozilla developers network

Please note that `Array.filter` needs a ECMAScript 5th edition compilant environment.

Example implementations

1. Reassing the `options_array` value

var options_array = [ 'foo', 'bar', 'baz', 'bicycle', 'motorbike' ];

options_array = options_array.filter(function(value){
  return value == 'bicycle';
});
// options_array is now [ 'foo', 'bar', 'baz', 'motorbike' ]

2. Reusable function to do the same as example #1

var options_array = [ 'foo', 'bar', 'baz', 'bicycle', 'motorbike' ];

function remove_option( option_name ){
  options_array = options_array.filter(function(value){
    return value == 'bicycle';
  });
}

remove_option( 'bicycle' );
// options_array is now [ 'foo', 'bar', 'baz', 'motorbike' ]
remove_option( 'foo' );
// options_array is now [ 'bar', 'baz', 'motorbike' ]

3. Reusable function to do the same as example #2 but with any array

var options_array = [ 'foo', 'bar', 'baz', 'bicycle', 'motorbike' ];
var options_array2 = [ 'foo', 'bar', 'baz' ];

function remove_option( options_array, option_name ){
  options_array = options_array.filter(function(value){
    return value == 'bicycle';
  });
}

remove_option( options_array, 'bicycle' );
// options_array is now [ 'foo', 'bar', 'baz', 'motorbike' ]
remove_option( options_array2, 'foo' );
// options_array2 is now [ 'bar', 'baz', 'bicycle', 'motorbike' ]

You could even build an object prototype to manage option arrays if its need, but i think the examples are enought.

answered Oct 8, 2013 at 14:25

laconbass

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3 Comments

zeth Over a year ago

Didn't know about array.filter - thanks for so many examples. I think you have made small mistake and there should be return value != 'bicycle'; for removing option. Nonetheless I like this solution and will go with it.

laconbass Over a year ago

Take Care and read the documentation carefully!! from the Array.prototype.filter reference Creates a new array with all elements that pass the test implemented by the provided function. filter calls a provided callback function once for each element in an array, and constructs a new array of all the values for which callback returns a true value.

laconbass Over a year ago

@zeth I forgot to mention you on the previous comment. Please check again the documentation link, return value == 'bicycle' is not a mistake.

Arun P Johny · Accepted Answer · 2013-10-08 13:45:06Z

0

Try

options_array = []

//this can be enhanced to support multiple elements like 'motorbike, tricycle'
var related = {
    'bicycle': 'motorbike',
    'motorbike': 'bicycle'
}

function remove_option(option) {
    remove_opts(option)
    var relation = related[option];
    if (relation) {
        remove_opts(relation)
    }
}

function remove_opts(option){
    var option_index = options_array.indexOf(option);
    if (option_index != -1) options_array.splice(option_index, 1);
}

answered Oct 8, 2013 at 13:45

Arun P Johny

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1 Comment

mbx-mbx Over a year ago

This could get quite tedious to maintain with many items especially when you have multiple relationships. A hierarchical approach of objects (where objects have a type and a parent type) may be better. Although for small examples like the one the OP posted this will probably be ok.

musefan · Accepted Answer · 2013-10-08 14:07:43Z

How about using an array of synonyms for each word:

var synonyms = [
    ['bicycle', 'motorbike'],
    ['car', 'van']
];

Then you can get the matching list with a helper function:

//this will return an array of related words (e.g. ['bicycle', 'motorbike'])
function getSynonyms(item) {
    for (var i = 0; i < synonyms.length; i++) {
        var arr = synonyms[i];
        for (var j = 0; j < arr.length; j++) {
            if (arr[j] == item) return arr;
        }
    }
    return null;
}

and finally your remove function can be changed like so:

//this will remove the option plus any matching synonym words
function remove_option(option) {
    var synonymsToRemove = getSynonyms(option);
    //check if any matches found, if not then just used the single specified option
    if (!synonymsToRemove) synonymsToRemove = [option];

    for (var i = 0; i < synonymsToRemove.length; i++) {
        var option_index = options_array.indexOf(synonymsToRemove[i]);
        if (option_index != -1) {
            options_array.splice(option_index, 1);
        }
    }
}

Which you can use like so:

console.log(options_array);//["bicycle", "motorbike", "car", "van"]
remove_option('bicycle');//remove 'bicycle' and related words (i.e. 'motorbike')
console.log(options_array);//["car", "van"]

Here is a working example

mcgrailm · Accepted Answer · 2013-10-08 18:45:50Z

0

You can use and alias array and loop through them

var options_array = ["motorbike",'bicycle','bike','car','vanagon'];

function remove_option(option,alias_array) {
    var option_index = options_array.indexOf(option);
    if(option_index != -1){
        if(alias_array.indexOf(option) != -1){
            for (var i=0;i<alias_array.length;i++){ 
                alias_index = options_array.indexOf(alias_array[i]);
                if(alias_index != -1){
                    options_array.splice(alias_index, 1);
                }   
            }
        }
    }
    return options_array;
}

console.log(remove_option('bike',['motorbike','bicycle','bike']));

edited Oct 8, 2013 at 18:45

answered Oct 8, 2013 at 13:49

mcgrailm

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removing strings from array with conditions

4 Answers 4

See Array.prototype.filter reference on mozilla developers network

Please note that `Array.filter` needs a ECMAScript 5th edition compilant environment.

Example implementations

1. Reassing the `options_array` value

2. Reusable function to do the same as example #1

3. Reusable function to do the same as example #2 but with any array

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Collectives™ on Stack Overflow

4 Answers 4

See Array.prototype.filter reference on mozilla developers network

Please note that Array.filter needs a ECMAScript 5th edition compilant environment.

Example implementations

1. Reassing the options_array value

2. Reusable function to do the same as example #1

3. Reusable function to do the same as example #2 but with any array

3 Comments

1 Comment

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Please note that `Array.filter` needs a ECMAScript 5th edition compilant environment.

1. Reassing the `options_array` value