Can I pass an array into fromCharCode

Question

I might be asking the wrong question here, so I apologize if the answer is on another thread... but I've looked around to no avail.

in a snippet, why doesn't this work?

array = [72,69,76,76,79];
document.write(String.fromCharCode(array));

I'm collecting key events in an array and want to be able to write them out as chars when prompted. And though this works:

document.write(String.fromCharCode(72,69,76,76,79));

I can't seem to get it to work when I pass it along as an array. I've also tried to convert the array toString() first, as well array.join(","); to create a comma separated list ...yet nothing. Any ideas? Is there a better way to convert the values I collect in my array into chars?

Answer 1

You could use the function's apply() method...

document.write(String.fromCharCode.apply(null, array));

jsFiddle.

ES6 can use the spread operator...

document.write(String.fromCharCode(...array));

You could also use the array's reduce() method, but older IEs do not support it. You could shim it, but the apply() method is better supported.

document.write(array.reduce(function(str, charIndex) {
    return str += String.fromCharCode(charIndex);
}, ''));​

jsFiddle.

Answer 2

Yes, you can use apply() to call a function which an array passed in as its arguments:

array = [72,69,76,76,79];
document.write(String.fromCharCode.apply(String, array));

Answer 3

If you use .apply() to call the fromCharCode() function, you can pass it an array that will be converted into arguments for the function like this:

document.write(String.fromCharCode.apply(this, array));

You can see it work here: http://jsfiddle.net/jfriend00/pfLLZ/

Answer 4

The method is more meant to be used like this:

document.write(String.fromCharCode(72,69,76,76,79));

You're passing in an array when the method expects multiple parameters as a list.

Answer 5

You may have to use a loop as follows

for(var i = 0; i < array.length; i++)
       document.write(String.fromCharCode(array[i]));
}

Answer 6

Here's 2 ways that I would do it:

var arr=[119,119,119,46,87,72,65,75,46,99,111,109];
document.write(eval('String.fromCharCode('+arr+')'));

document.write('<hr>');

var arr='119,119,119,46,87,72,65,75,46,99,111,109';
document.write(eval('String.fromCharCode('+arr+')'));

Answer 7

Here is a function:

var unCharCode = function(x) {
  return this["eval"]("String['fromCharCode'](" + x + ")");
};

document.write(unCharCode([ 119, 119, 119, 46, 87, 72, 65, 75, 46, 99, 111, 109 ]));

document.write("<hr>");

document.write(unCharCode("119,119,119,46,87,72,65,75,46,99,111,109"));