I have variable var str as following:
var str = ;
I would like to make it as below
I think that you want the semicolon outside the string literal:
var quote_str = '';
If you mean that you want apostrophe characters inside the string also, you can use \' to put an apostrophe in a string delimited by apostrophes:
var quote_str = '\'\'';
You can also use quotation marks to delimit the string. Then you don't have to escape the apostrophes, but you have to escape the quotation marks:
var quote_str = "''";
If you already have a string, and want to add apostrophes around it, you concatenate strings:
var quote_str = "'" + str + "'";