How can I tell if string contains both a Single-quote (') and a double-quote (")?

A quick way to check if the string contains both a single quote and a double quote.

if (str.indexOf('\'') >= 0 && str.indexOf('"') >= 0) {
   //do something
}

edit: if the character is in the first position, indexOf will return zero.

I'm guessing you want something like /['||"]/.test(str);