Random char in a .js file

This is the chars: "*+-/";

Javascript getElementById

How can i do "randt" to be 1 random char?

So if i type:

document.getElementById("sms-text").innerHTML = "" + random2 开发者_StackOverflow+ randt;

It will be for ex "22*" or "51+"

How do i do it?

If I understand your question correctly, you will take a random number 0-3, then find the character at that position;

var signs = "*+-/";

var signId = Math.floor(Math.random() * signs.length);

var sign = signs.charAt(signId);

var str = "*+-/";
var random_char = str[Math.floor(Math.random() * str.length)];

As the other answers point out, str.charAt() would also work.

This is pretty simple to do with a combination of Math.random() and Math.floor():

var chars = "*+-/",
    randt = chars[Math.floor(Math.random() * 4)];

Note that you could replace 4 with chars.length if you don't know how many characters are in chars.

Simply just grab a random number from 0 to the length of the string and then cut the char out like so

var chars = "+-/";
var char = chars[Math.floor(Math.random() * chars.length)];

using char would be the random character

alternatively you can add the rand method to the prototype like so

String.prototype.randChar = function()
{
    return this[Math.floor(Math.random() * this.length)];
}

and then within any string created you can use like so

char = "+-.".randChar();

This is basically the same question as you asked before, only with the difference that you are using innerHTML instead of document.write. The way to produce the string is the same, so you can just use the function from my previous answer:

function makeid(lastNumber) {
  var possible = "*+-/";
  return lastNumber + possible.charAt(Math.floor(Math.random() * possible.length));
}

Usage:

document.getElementById("sms-text").innerHTML = makeid(random2);

var randt=['*','+','-','/'][Math.floor(Math.random()*4)];