CODEWITHSUNDEEP
javascriptjquerylodash
Thian Kian Phin
Thian Kian Phin

Reputation: 931

Check if array of object value exist in another array but different length

I have 2 array of object, just want to check b exist in a, if yes add a new property. but the length of b is dynamic. I will got error of undefined of b.

var a = [{name:'john'},{name:'james'},{name:'jordan'},{name:'joe'}];
var b = [{name:'john'},{name:'joe'}];

var exist = 0;
var c = _.map(a,function(result,i){
    exist = b[i].name.indexOf(a.name) > -1 ? exist = 1 : exist = 0;

    return _.extend({},c,{'exist':exist});
});

any clue?

Upvotes: 1

Views: 925

Answers (3)

naortor
naortor

Reputation: 2089

I would iterate over b objects and for each of them check if they exists in A, like in the following example.

    var a = [ { _id: '5815adb4badf3f311a2cd25b', username: 'david&jane' },
    { _id: '5815e40e136c8e33b65b3478', username: 'david+jane' } ];
    var b = [ { username: 'david&jane' },
              { username: 'david<3jane' },
              { username: 'david+jane' },
              { username: 'davidjane' } 
    ]
    var c = [];

    b.forEach(function(user) {
      var exists = false;
      for (let i=0; i<a.length && !exists; i++){
          exists = a[i].username === user.username ;
      }
      
      c.push(Object.assign({},user,{exists}));
    });

    console.log(c);

Upvotes: 3

adeneo
adeneo

Reputation: 318202

You could use Array.every to check that every object in b is also in a, and in the callback you could use Array.some to check a for keys and values

var a = [{name:'john'},{name:'james'},{name:'jordan'},{name:'joe'}];
var b = [{name:'john'},{name:'joe'}];

var exist = b.every( (o) => {
    let k = Object.keys(o)[0];
    return a.some( p => k in p && p[k] === o[k]);
});

console.log(exist)

If you want to add properties, you can do that as well

var a = [{name:'john'},{name:'james'},{name:'jordan'},{name:'joe'}];
var b = [{name:'john'},{name:'joe'}];

var c = b.map( (o) => {
    let k = Object.keys(o)[0];
    return o.exist = a.some( p => k in p && p[k] === o[k]), o;
});

console.log(c);

Upvotes: 1

Pranesh Ravi
Pranesh Ravi

Reputation: 19113

First stringify a array. Loop through b and create a dynamic regex to test on a if the test matches do your stuff.

Hope this helps!

var a = [{name:'john'},{name:'james'},{name:'jordan'},{name:'joe'}];
var b = [{name:'john'},{name:'joe'}, {name:'hello'}];

var strA = JSON.stringify(a)

var result = b.map((el) => {
  var elStr = JSON.stringify(el)
  var regex = new RegExp(elStr, 'g')
  if(regex.test(strA))
     return Object.assign({}, el, {exist: 1})
  return Object.assign({}, el, {exist: 0})
})

console.log(result)

Upvotes: 1

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