plastikaweb
11/14/2017 - 12:21 PM

JS Bin joins with map-filter-reduce // source http://jsbin.com/waqojed

JS Bin

joins with map-filter-reduce

// source http://jsbin.com/waqojed

index.html
content_copyfile_download
<!DOCTYPE html>
<html>
<head>
<meta name="description" content="joins with map-filter-reduce">
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>

<script id="jsbin-javascript">
'use strict';

var students = [{
  id: 1,
  name: 'Carlos'
}, {
  id: 2,
  name: 'Lola'
}, {
  id: 3,
  name: 'Max'
}];
var tests = [{
  id: 1,
  studentID: 1,
  title: 'Fractals'
}, {
  id: 2,
  studentID: 1,
  title: 'Javascript'
}, {
  id: 3,
  studentID: 2,
  title: 'Fractals'
}, {
  id: 4,
  studentID: 3,
  title: 'Javascript'
}];
var result = students.map(function (student) {
  var reducer = function reducer(count, test) {
    return test.studentID === student.id ? count + 1 : count;
  };

  var testCount = tests.reduce(reducer, 0);

  return {
    studentName: student.name,
    testCount: testCount
  };
});

var result2 = students.map(function (student) {
  var filter = tests.filter(function (test) {
    return test.studentID === student.id;
  });

  var testCount = filter.length;

  return {
    studentName: student.name,
    testCount: testCount
  };
});

console.log(result);
console.log(result2);
</script>



<script id="jsbin-source-javascript" type="text/javascript">const students = [
  {
    id: 1,
    name: 'Carlos'
  },
  {
    id: 2,
    name: 'Lola'
  },
  {
    id: 3,
    name: 'Max'
  }
];
const tests = [
  {
    id: 1,
    studentID: 1,
    title: 'Fractals'
  },
  {
    id: 2,
    studentID: 1,
    title: 'Javascript'
  },
  {
    id: 3,
    studentID: 2,
    title: 'Fractals'
  },
  {
    id: 4,
    studentID: 3,
    title: 'Javascript'
  }
];
const result = students.map( student => {
  const reducer = (count, test) =>  
    test.studentID === student.id ? count + 1 : count;
  
  const testCount = tests.reduce(reducer, 0);
  
  return {
    studentName: student.name,
    testCount: testCount
  };
});

const result2 = students.map( student => {
  const filter = tests.filter(test =>
    test.studentID === student.id);
  
  const testCount = filter.length;
  
  return {
    studentName: student.name,
    testCount: testCount
  };
});


console.log(result);
console.log(result2);</script></body>
</html>
jsbin.waqojed.js
content_copyfile_download
'use strict';

var students = [{
  id: 1,
  name: 'Carlos'
}, {
  id: 2,
  name: 'Lola'
}, {
  id: 3,
  name: 'Max'
}];
var tests = [{
  id: 1,
  studentID: 1,
  title: 'Fractals'
}, {
  id: 2,
  studentID: 1,
  title: 'Javascript'
}, {
  id: 3,
  studentID: 2,
  title: 'Fractals'
}, {
  id: 4,
  studentID: 3,
  title: 'Javascript'
}];
var result = students.map(function (student) {
  var reducer = function reducer(count, test) {
    return test.studentID === student.id ? count + 1 : count;
  };

  var testCount = tests.reduce(reducer, 0);

  return {
    studentName: student.name,
    testCount: testCount
  };
});

var result2 = students.map(function (student) {
  var filter = tests.filter(function (test) {
    return test.studentID === student.id;
  });

  var testCount = filter.length;

  return {
    studentName: student.name,
    testCount: testCount
  };
});

console.log(result);
console.log(result2);