Question

我有一个值重复的数组，如何列出这些值

var result = [ { name: 'Maura Hickman' },
  { name: 'Elena Vega' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' },
  { name: 'Luisa Rutledge' },
  { name: 'Pearson Marquez' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' } ]

我尝试这样做

var obj = [ { name: 'Maura Hickman' },
  { name: 'Elena Vega' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' },
  { name: 'Luisa Rutledge' },
  { name: 'Pearson Marquez' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' } ];
if (Object.values(obj).indexOf('Jana Stevenson') > -1) {
   console.log('has Jana Stevenson');
}

但是没有用。

我期望的是以下

var exist =  [{ name: 'Jana Stevenson'} , {name: 'Sylvia Norman' },
{ name: 'Colon Reynolds'}]

Answer 1

您可以使用filter()和findIndex()

var arr = [ { name: 'Maura Hickman' },
  { name: 'Elena Vega' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' },
  { name: 'Luisa Rutledge' },
  { name: 'Pearson Marquez' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' },
  { name: 'Colon Reynolds' }]
  
const res = arr.filter((x,i) => arr.findIndex(a => a.name === x.name) !== i)
               .filter((x,i,arr) => arr.find(a => a.name === x.name) === x);
              
console.log(res)

Answer 2

尝试使用Array#prototype#reduce，维护一个辅助对象，如果该键尚未在累加器中添加，请将其添加，否则将其推入累加器，最后返回累加器。

result = [{
    name: 'Maura Hickman'
  },
  {
    name: 'Elena Vega'
  },
  {
    name: 'Sylvia Norman'
  },
  {
    name: 'Sylvia Norman'
  },
  {
    name: 'Sylvia Norman'
  },
  {
    name: 'Jana Stevenson'
  },
  {
    name: 'Colon Reynolds'
  },
  {
    name: 'Luisa Rutledge'
  },
  {
    name: 'Pearson Marquez'
  },
  {
    name: 'Sylvia Norman'
  },
  {
    name: 'Jana Stevenson'
  },
  {
    name: 'Colon Reynolds'
  }
];

// Take the groups which have more than 1 element in it
const duplicateNames = Object.values(result.reduce((acc, curr) => {
  // If not existing in accumulator add it
  if (!acc[curr.name]) {
		acc[curr.name] = [curr];
  }

  // Else push it simply
  else {
	acc[curr.name].push(curr);
  }

  return acc;
}, {}))
.filter(x => x.length > 1)
.map(x => x[0]);

console.log(duplicateNames);

Answer 3

您可以将Set用作找到的名称，如果找到该对象，则取该对象；如果找不到，则将该名称添加到集合中并返回false。

var array = [{ name: 'Maura Hickman' }, { name: 'Elena Vega' }, { name: 'Sylvia Norman' }, { name: 'Jana Stevenson' }, { name: 'Colon Reynolds' }, { name: 'Luisa Rutledge' }, { name: 'Pearson Marquez' }, { name: 'Sylvia Norman' }, { name: 'Jana Stevenson' }, { name: 'Colon Reynolds' }],
    found = new Set,
    duplicates = array.filter(({ name }) => found.has(name) || !found.add(name));

console.log(duplicates);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 4

例如：

var check = 'Elena Vega';

var result = [ 
  { name: 'Maura Hickman' },
  { name: 'Elena Vega' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' },
  { name: 'Luisa Rutledge' },
  { name: 'Pearson Marquez' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' } 
]

var i
for( i = 0; i < result.length; i++ ){
  if( result[i].name == check ) {
    console.log( 'Found Match: «' + check + '» at result[' + i + '];' );
    break;
  }
}

P.s。如果您的数组对象仅包含.name键，则可以仅使用数组，如下所示：

var result = [
  'Maura Hickman',    // == result[0]
  'Elena Vega',       // == result[1]
  'Sylvia Norman',    // == result[2] etc.
  'Jana Stevenson',
  'Colon Reynolds',
  'Luisa Rutledge',
  'Pearson Marquez',
  'Sylvia Norman',
  'Jana Stevenson',
  'Colon Reynolds'
]

Answer 5

您有一个数组，而不是对象，因此Object.values()仅将返回整个数组。尝试filtering数组。

var obj = [ { name: 'Maura Hickman' },
  { name: 'Elena Vega' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' },
  { name: 'Luisa Rutledge' },
  { name: 'Pearson Marquez' },
  { name: 'Sylvia Norman' },
  { name: 'Jana Stevenson' },
  { name: 'Colon Reynolds' } ];

var hasJana = obj.filter(itm=>itm.name=='Jana Stevenson').length>0;

if (hasJana) {
   console.log('has Jana Stevenson');
}

Answer 6

首先，您拥有一个数组，而不是一个对象。事实证明，您不应该调用数组对象，这很令人困惑。从{} !== {}开始，您需要实际检查要确保唯一的属性。您可以使用以下reducer，然后重新创建对象数组结构。

const res = arr.reduce((a, {name}) => ! a.includes(name) ? a.concat(name) : a, []).map(name => ({name}));
console.log(res)

<script>
const arr = [ { name: 'Maura Hickman' },
    { name: 'Elena Vega' },
    { name: 'Sylvia Norman' },
    { name: 'Jana Stevenson' },
    { name: 'Colon Reynolds' },
    { name: 'Luisa Rutledge' },
    { name: 'Pearson Marquez' },
    { name: 'Sylvia Norman' },
    { name: 'Jana Stevenson' },
    { name: 'Colon Reynolds' } ];
</script>

列出数组中的重复值

6 个答案: