This idea came when I was trying to implement a reusable code library. The method I called forWhich. So I thought, having it as an improvement on forEach would be better.
So here goes the definition:
forEach element in this array, execute this callback function, (optionally)provided it returns true for this predicate function
- This eases the work of having to filter() an array for elements you don't want, before performing an action on all of them.
- Also eases the work of, having to find() an element in an array before performing an action on it
- It is a good refactoring code for these task.
- It would be very useful in DOM manipulation, as the
forEachmethod is used most in that case(I think). - More Importantly: It's not every case I would want to filter my array. I might want to manipulate one or some of the array elements.
- Consider: Which one would be faster: having to filter an array first before executing callback or checking for condition on an array item before executing callback
- There are a lot ways to solve a problem, but we aim for speed and less memory
Syntax:
array.forEach(callback, [predicate]);
Sample code:
Make each element's background blue provided it has the blue class. Although this is one that could be done easily in css with a class.
[DOMelem1, DOMelem2, ...]
.forEach((el) => {
// callback func
makeBgBlue(el);
},
(el) => {
// predicate func
return el.classlist.contains('make-blue');
});
Sample code 2:
Multiply each obj's x property by 2, provided its id property is equal to 'someId'
[obj1, obj2, ...]
.forEach((obj) => obj.x * 2, (obj) => obj.id === 'someId');
I don't know how this would be implemented, it may require a new Array method... As I know the TC39 wouldn't wanna break existing code, which in this case the thisArg parameter, which would normally be the second parameter to the function.
I was also thinking it could be implemented for the map array method also, but I haven't thought that through.
Thanks for considering this proposal.
JS 
- Kehinde Ogunrinola