Javascript

Create an regular expression object

Replace string 'aaa' by 'xyz'.

   1 var stringx = 'aaa bbb ccc';
   2 var regexx = new RegExp('aaa','g');
   3 stringx = stringx.replace( regexx , 'xyz' );

Delete property from object

   1 delete obj['propertyName'];

Number of milliseconds since epoch

   1 var nrmillis = Date.now();

Foreach in array

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach

function logArrayElements(element, index, array) {
    console.log("a[" + index + "] = " + element);
}
[2, 5, 9].forEach(logArrayElements);
// logs:
// a[0] = 2
// a[1] = 5
// a[2] = 9