Array - push is not a function (javascript)

var name = ['a', 'b', 'c']; 
name.push('d'); 

There was an error doing this. name.push is not a function

However, there was no problem because the variable name was changed from name to a as follows.

var a = ['a', 'b', 'c']; 
a.push('d');

Just in case Through JavaScript Variable name Validator I checked if name is a variable that should not be used, but it was okay. Why is it like this?