JavaScript array manipulation to delete odd array elements

Question

I need help; I have an array like this:

myarray = ["nonsense","goodpart","nonsense2","goodpar2t","nonsense3","goodpart3",]

I need to delete all "nonsense" part from array.

Nonsense always have an even index.

Answer 1

I'd suggest, on the basis that 'nonsense' words are always (as stated in the question) the 'even' elements:

 var myarray = ["nonsense", "goodpart", "nonsense2", "goodpar2t", "nonsense3", "goodpart3"], filtered = myarray.filter(function(el, index) { // normally even numbers have the feature that number % 2 === 0; // JavaScript is, however, zero-based, so want those elements with a modulo of 1: return index % 2 === 1; }); console.log(filtered); // ["goodpart", "goodpar2t", "goodpart3"] 

If, however, you wanted to filter by the array-elements themselves, to remove all words that contain the word 'nonsense':

 var myarray = ["nonsense", "goodpart", "nonsense2", "goodpar2t", "nonsense3", "goodpart3"], filtered = myarray.filter(function(el) { // an indexOf() equal to -1 means the passed-in string was not found: return el.indexOf('nonsense') === -1; }); console.log(filtered); // ["goodpart", "goodpar2t", "goodpart3"] 

Or to find, and keep, only those words that begin with 'good' :

 var myarray = ["nonsense", "goodpart", "nonsense2", "goodpar2t", "nonsense3", "goodpart3"], filtered = myarray.filter(function(el) { // here we test the word ('el') against the regular expression, // ^good meaning a string of 'good' that appears at the beginning of the // string: return (/^good/).test(el); }); console.log(filtered); // ["goodpart", "goodpar2t", "goodpart3"] 

References:

• Array.prototype.filter() .
• Array.prototype.indexOf() .
• JavaScript regular expressions .
• RegExp.prototype.test() .
• String.prototype.indexOf() .

Answer 2

This is just a slight variation to @DavidThomas's great answer (+1). This will be helpful in case you decide to exclude array members by value ( nonsense ) instead of by position ( odd ):

var myarray = ["nonsense", "goodpart", "nonsense2", "goodpar2t", "nonsense3", "goodpart3"],
    filtered = myarray.filter(function(el) {
        //return only values that do not contain 'nonsense'
        return el.indexOf('nonsense') === -1;
    });

 var myarray = ["nonsense", "goodpart", "nonsense2", "goodpar2t", "nonsense3", "goodpart3"], filtered = myarray.filter(function(el) { //return only values that do not contain 'nonsense' return el.indexOf('nonsense') === -1; }); //output result $('pre.out').text( JSON.stringify( filtered ) ); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <pre class="out"></div>