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Problem

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You want to remove duplicates from arrays.

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Ingredients

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Directions

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    \n
  1. \n

    Given: an array with duplicate values.

    \n
    let array = ['John', 'James', 'John', 'Jane', 'John'];\nlet result = removeDuplicates(array);\nconsole.log(result);\n// expected content of array3: ['John', 'James', 'Jane']
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    2. \n
  2. \n

    Create the removeDuplicates function and inside create a copy of the array parameter\n(e.g., by using the concat() method).

    \n
    function removeDuplicates(array) {\n  let result = array.concat();\n  ...\n  return result;\n}
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    3. \n
  3. \n

    Iterate over each element in the copy.

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    function removeDuplicates(array) {\n  let result = array.concat();\n  for(let i=0; i<result.length; ++i) {\n    ...\n  }\n  return result;\n}
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    4. \n
  4. \n

    For each element iterate over all the other elements.

    \n
    function removeDuplicates(array) {\n  let result = array.concat();\n  for(let i=0; i<result.length; ++i) {\n    for(let j=i+1; j<result.length; ++j) {\n      ...\n    }\n  }\n  return result;\n}
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    5. \n
  5. \n

    Compare the element with each other element.

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    function removeDuplicates(array) {\n  let result = array.concat();\n  for(let i=0; i<result.length; ++i) {\n    for(let j=i+1; j<result.length; ++j) {\n      if(result[i] === result[j]) {\n        ...\n      }\n    }\n  }\n  return result;\n}
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    6. \n
  6. \n

    If both elements are equal (===) then delete the duplicate using the splice() method.

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    function removeDuplicates(array) {\n  let result = array.concat();\n  for(let i=0; i<result.length; ++i) {\n    for(let j=i+1; j<result.length; ++j) {\n      if(result[i] === result[j]) {\n        result.splice(j--, 1);\n      }\n    }\n  }\n  return result;\n}
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    7. \n
  7. \n

    Voilá, there you got a function which removes duplicates from an array.

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    let array = ['John', 'James', 'John', 'Jane', 'John'];\nlet result = removeDuplicates(array);\nconsole.log(result); // ['John', 'James', 'Jane']
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    8. \n
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Notes

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Alternative recipes

\n","fields":{"slug":"/posts/en/2016-07-09-remove-duplicates-from-arrays/","tagSlugs":["/tag/java-script/"]},"frontmatter":{"date":"2016-07-09T08:00:00.000Z","description":null,"tags":["JavaScript"],"title":"Remove duplicates from arrays"}}},"pageContext":{"isCreatedByStatefulCreatePages":false,"slug":"/posts/en/2016-07-09-remove-duplicates-from-arrays/"}}}