javascript add to array – 3 Ways to Append Item to Array (Mutative) using push, splice and length. also 2 Ways to Append Item to Array (Non Mutative) like concat and spread.
javascript add to array – JavaScript Array push() Method
Main 3 Ways to Append Item to Array (Mutative)
using push
The simplest way to add items to the end of an array is to use push.
const team = ['?', '?'];
team.push('?');
console.log(team); // ['?', '?', '?']
const team = ['?', '?'];
team.push('?', '?', '?');
console.log(team); // ['?', '?', '?', '?', '?']
const team = ['?', '?']; const birds = ['?', '?', '?']; team.push(...birds); console.log(team); // ['?', '?', '?', '?', '?']
Using splice
| Parameters | Parameter Name | Definition |
|---|---|---|
| 1 | startIndex | The index where you want to add/remove item |
| 2 | deleteCount | The number of items you want to remove |
| 3 | items | The number you want to add (If you’re removing, you can just leave this blank) |
const team = ['?', '?']; team.splice( team.length, // We want add at the END of our array 0, // We do NOT want to remove any item '?', '?', '?', // These are the items we want to add ); console.log(team); // ['?', '?', '?', '?', '?']
Using length
const team = ['?', '?']; // '?' | Index = 0 // '?' | Index = 1
The bracket notation in arrays
const team = ['?', '?']; // Retrieve team[0]; // Returns '?' // Override team[1] = '?'; console.log(team); // ['?', '?']; ** // ** JUST JOKING ? // ...I promise no workers were hurt in this blog article ?
using array.length
const team = ['?', '?']; const length = team.length; // 2 team[length] = '?'; console.log(team); // ['?', '?', '?']
2 Ways to Append Item to Array (Non Mutative)
concat
const players = ['?', '?']; const bolower = ['?', '?']; const allrounders = players.concat(bolower); allrounders; // ['?', '?', '?', '?'] // Original Array Not Affected players; // ['?', '?']
const players = ['?', '?'];
const allrounders = players.concat('?');
const renews = players.concat('?', '?');
allrounders; // ['?', '?', '?']
renews; // ['?', '?', '?', '?']
// Original Array Not Affected
players; // ['?', '?']
Don’t Miss : javascript push array into array
spread
const players = ['?', '?']; const bolower = ['?', '?']; const allrounders = [...players, ...bolower]; allrounders; // ['?', '?', '?', '?'] // Original Array Not Affected players; // ['?', '?']
const players = ['?', '?']; const bolower = ['?', '?']; const allrounders = [players, bolower]; // [ ['?', '?'], ['?', '?'] ]
const players = ['?', '?']; const allrounders = [...players, '?']; const renews = [...players, '?', '?']; allrounders; // ['?', '?', '?'] renews; // ['?', '?', '?', '?'] // Original Array Not Affected players; // ['?', '?']
To Mutate Or Not to Mutate?
function menu(isRekha) {
const player = ['?', '?'];
isRekha ? player.push('?') : player;
return player;
}
Community Input
add an empty item to an array
const resultsPlayers = [1, 2]; resultsPlayers.length = 3; console.log(resultsPlayers); // [1, 2, <1 empty item>]
use it to shrink array
const resultsPlayers = [1, 2]; resultsPlayers.length = 1; console.log(resultsPlayers); // [1]
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