Run results for: Shallow copy performance

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36

Browser: Chrome 71

Operating system: Mac OS X 10.13.6

Device Platform: Desktop

Date tested: 6 years ago

Script Preparation code:

var data = [];
var res = [];

fetch('https://jsonplaceholder.typicode.com/posts')
  .then(response => response.json())
  .then(json => data = json)

​x
 
var data = [];var res = [];​fetch('https://jsonplaceholder.typicode.com/posts')  .then(response => response.json())  .then(json => data = json)

Tests:

slice
res = data.slice();
res = data.slice();
concat
res = data.concat();
res = data.concat();
forEach
res = []; data.forEach(element => res.push(element));
res = [];
data.forEach(element => res.push(element));
Traditional For Loop
res = []; for (let i = 0; i < data.length; i++) { res.push(data[i]); }
res = [];
for (let i = 0; i < data.length; i++) {
res.push(data[i]);
}