How can I check for uniqueness in Javascript?

Question

I have a dropdown-menu.

JS

$.each(responseData.assignments, function(i, v) {

    var assessmentId = v.assessmentId;
    var assessmentType = v.assessmentType;

    // Auto Populate the dropdown-menu
    $('#student-dd').append('<option value="' + assessmentId + '">' + assessmentType + '</option>');

});

Goal I want to show only one HOMEWORK/COURSE_BENCHMARK, doesn't matter how many of them are there. How can I check for uniqueness in Javascript ?

try this: http://stackoverflow.com/questions/1960473/unique-values-in-an-array — atmd, Aug 20 '15 at 13:27

Milind Anantwar · Accepted Answer · 2015-08-20T13:35:24.070

3

You can check for length of option element with same text in that dropdown using filter function before appending new:

$.each(responseData.assignments, function(i, v) {

  var assessmentId = v.assessmentId;
  var assessmentType = v.assessmentType;

  // Auto Populate the dropdown-menu

  var optionwithsametext = $('#student-dd option').filter(function(){
      return $(this).text() == assessmentType ;
  })
  if(!optionwithsametext.length)
    $('#student-dd').append('<option value="' + assessmentId + '">' + assessmentType + '</option>');

 });

edited Aug 20 '15 at 13:35

answered Aug 20 '15 at 13:27

Milind Anantwar

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But won't the `value` always be different as it is an `ID`? You should instead look at the `assessmentType`, which is the `text`. – ᔕᖺᘎᕊ Aug 20 '15 at 13:31
@ᔕᖺᘎᕊ: quite possible. modified the answer. – Milind Anantwar Aug 20 '15 at 13:35

score 1 · Answer 2 · answered Aug 20 '15 at 13:35

There is more than one way to do this. This is an another example;

var assignments = {};
$.each(responseData.assignments, function(i, v) {
    assignments[v.assessmentType] = v.assessmentId;
});

$.each(assignments, function(i, v) {
    // Auto Populate the dropdown-menu
    $('#student-dd').append('<option value="' + v + '">' + i + '</option>');
});

How can I check for uniqueness in Javascript?

2 Answers2