An array reference problem for JavaScript strings

One recent project encountered a pit, which is an array reference to a JS string:

Javascript

var str = ' ABCDEFG ';

A character that refers to the 3rd position of the string
Alert (str[2]);
Most browsers output normal value of C; However, some low-level browsers (such as IE7) do not support such references, and the output is undefined.

In order to achieve compatibility, after the honest use of the String.charat method ~

var str = ' ABCDEFG ';

A character that refers to the 3rd position of the string
Alert (Str.charat (2));