How to get nth character in a string in Javascript?

Let me summarize the possibilities

given:

var string = "HAI";
/* and */
var index = 1; // number ∈ [0..string.length), rounded down to integer

• string.charAt(index) returns "A" (preferred)
• string[index] returns "A" (non-standard)
• string.substring(index, index+1) returns "A" (over-complex solution but works)
• string.substr(index, 1) returns "A" (non-standard approach to above)