JavaScript - Push multiple results from for loop into array

Question

I have created a basic system to output users that match with the same genre interests as a specified user. I want to push the results of the for loop into an array however I can only get the last for loop output to be pushed into the array but I want all of the results to be 'pushed'. Any suggestions?

// User database
var jon = {username: 'Jon', genrePref: 'Rock'};
var lucy = {username: 'Lucy', genrePref: 'Pop'};
var mike = {username: 'Mike', genrePref: 'Rock'};
var luke = {username: 'Luke', genrePref: 'House'};
var james = {username: 'James', genrePref: 'House'};
var dave = {username: 'Dave', genrePref: 'Bass'};
var sarah = {username: 'Sarah', genrePref: 'Country'};
var natalie = {username: 'Natalie', genrePref: 'Bass'};

//userProfile.push()

// User database array
var userProfile = [jon, lucy, mike, luke, james, dave, sarah, natalie];


// Object containing username of logged in user and specification of the loaded track's genre
var trackGenre = {username: 'Harry', trackGenre: 'Rock'};

// For loop listing usernames of users with genre preference the same as the distributed track
for(i = 0; i < userProfile.length; i++){

  if(userProfile[i].genrePref == trackGenre.trackGenre){

    console.log(userProfile[i].username);

    var matchs = [];

    matchs.push(userProfile[i].username);

  }
}

console.log(matchs)

Answer 1

Move the declaration of var higher up - you are reinstatiating it every time, thus clearing it out:

var trackGenre = {username: 'Harry', trackGenre: 'Rock'};

var matchs = [];

// For loop listing usernames of users with genre preference the same as the distributed track
for(i = 0; i < userProfile.length; i++){

 if(userProfile[i].genrePref == trackGenre.trackGenre){

    console.log(userProfile[i].username);

    matchs.push(userProfile[i].username);

    }
}

Answer 2

As a supplementary answer to that posted by @Montagist I thought I'd show two alternative approaches to achieve your stated goal, the first using Array.prototype.forEach() , rather than a for loop, which also iterates over the array of users:

 // User database var jon = { username: 'Jon', genrePref: 'Rock' }; var lucy = { username: 'Lucy', genrePref: 'Pop' }; var mike = { username: 'Mike', genrePref: 'Rock' }; var luke = { username: 'Luke', genrePref: 'House' }; var james = { username: 'James', genrePref: 'House' }; var dave = { username: 'Dave', genrePref: 'Bass' }; var sarah = { username: 'Sarah', genrePref: 'Country' }; var natalie = { username: 'Natalie', genrePref: 'Bass' }; // User database array var userProfile = [jon, lucy, mike, luke, james, dave, sarah, natalie]; // Object containing username of logged in user and specification of the loaded track's genre var trackGenre = { username: 'Harry', trackGenre: 'Rock' }, matches = []; // iterating over the userProfile Array, using // Array.prototype.forEach(): userProfile.forEach(function(user) { // 'user', the first and only argument, is a // reference to the current Array element of // the Array over which we're iterating. // if the genrePref property of the current // user Object is equal to the trackGenre // property of the trackGenre Object: if (user.genrePref === trackGenre.trackGenre) { // we use Array.prototype.push() to add that // property to the matches Array: matches.push(user.username); } }); console.log(matches) // ["Jon", "Mike"] 

JS Fiddle demo .

And another using both Array.prototype.map() and Array.prototype.filter() :

 // User database var jon = { username: 'Jon', genrePref: 'Rock' }; var lucy = { username: 'Lucy', genrePref: 'Pop' }; var mike = { username: 'Mike', genrePref: 'Rock' }; var luke = { username: 'Luke', genrePref: 'House' }; var james = { username: 'James', genrePref: 'House' }; var dave = { username: 'Dave', genrePref: 'Bass' }; var sarah = { username: 'Sarah', genrePref: 'Country' }; var natalie = { username: 'Natalie', genrePref: 'Bass' }; // User database array var userProfile = [jon, lucy, mike, luke, james, dave, sarah, natalie]; // Object containing username of logged in user and specification of the loaded track's genre var trackGenre = { username: 'Harry', trackGenre: 'Rock' }, // Array.prototype.map() returns a new Array: matches = userProfile.map(function(user) { // 'user', the first and only argument here, is // a reference to the current Array element of // the Array over which we're iterating; here // it's an Object. // if the genrePref property of the current // user Object is exactly equal to the // trackGenre property of the trackGenre Object: if (user.genrePref === trackGenre.trackGenre) { // we return the username of the current // user Object return user.username; } // in those situations where the if condition evaluated // to false the anonymous function returns undefined; so // here we use Array.prototype.filter(), with a Boolean, // to retain only those array-elements which are true/truthy: }).filter(Boolean); console.log(matches) // ["Jon", "Mike"] 

JS Fiddle demo .

References:

• Array.prototype.filter() .
• Array.prototype.forEach() .
• Array.prototype.map() .