I use Math.random() right now, it returns some number like 0.7183306051883847. There're some bad sides of this function:
0. at the beginning
no option to set a symbols length of the number
no option to add letters to the string
I wonder, what is the shortest code to generate strings like (expected characters length - 6 for example)?
2en81u39438sldksfnThanks.
This should be the shortest. If you need it uppercased, add an extra .toUpperCase() call at the tail.
Math.random().toString(36).substring(3,9) Updated
This version is a bit longer, but it does avoid the problem that some special rational number may not have enough length.
(+new Date * Math.random()).toString(36).substring(0,6) 
btoa does the job, but not particularly well:
> btoa(Math.random()) "MC43MzU0MzQ4NTk5OTEwNzM2" > btoa(Math.random()) "MC44MTk2NzE0OTIzMjUxNDI=" > btoa(Math.random()) "MC41NDgwMzgxMzMxODcyMTk1" > btoa(Math.random()) "MC4wNTk4NDc1NDIzMTc1ODQxNg==" > btoa(Math.random()) "MC41NjA1NzYxNTEzNTc5NjM3" > btoa(Math.random()) "MC4xMTA5MzY5ODY5ODA5NTk3Nw==" > btoa(Math.random()) "MC42NDgwNzM5NjY2MTQ5MDI=" > btoa(Math.random()) "MC4zMTkzNTM2OTQzMjkwMzgyNg==" > btoa(Math.random()) "MC4yOTU2OTgyOTE4NTQ5MzI5" > btoa(Math.random()) "MC44ODc3MDEzNjQ0NjY5MjA1" Note how they all start with MC4, since Math.random().toString() always starts with 0.
function randomString() { var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz"; var string_length = 8; var randomstring = ''; for (var i = 0; i < string_length; i++) { var rnum = Math.floor(Math.random() * chars.length); randomstring += chars[rnum]; } return randomstring; } 
chars.substring(rnum, rnum + 1) => chars[rnum]
Get an array of ints that will be translated to your random string, something like this:
var myAscii = [], someAscii; for (var i = 0; i < 5; i +=1) { someAscii = Math.floor(Math.random() * (90 - 65)) + 65; // This gives you a random number between 65 and 90, which is the upper case A-Z. Adapt it to your stuff. myAscii.push(someAscii); } var randomString = String.fromCharCode.apply(someAscii); Anyway, it is a simpler approach to get a string with all the desired characters and perform a random extraction, as the related answer proposes.
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