Why Doesn't Any Object Prototype Work As A Foreach Callback?

Rather than a question, I just wanted it to be a challenge but couldn't find an answer yet. For example, we have an array of strings x = ['a', ' b', ' c '] and I want to trim

Solution 1:

foo.call() will call the function stored in foo.

i.e. the value of this inside call will be foo.

The function you pass to forEach gets called without explicit context, so the value of this will be the default object (window in a browser).

window is not a function, so it errors.

You can use bind to create a new function that calls a function with a specific context.

Solution 2:

Try this,

x = ['a', '   b', '  c  ']
x.map(function(item) { return item.trim() })