How to generate sequence of numbers/chars in javascript?

Question

Without a for loop, here is a solution:

Array.apply(0, Array(8)).map(function() { return 1; })

The explanation follows.

Array(8) produces a sparse array with 8 elements, all undefined. The apply trick will turn it into a dense array. Finally, with map, we replace that undefined the (same) value of 1.

The original question was edited. So the updated example answers:

To fill the same content:

Array(8).fill(1)
//=> [1, 1, 1, 1, 1, 1, 1, 1]

To fill sequential numbers, starting from 5:

Array(8).fill().map((element, index) => index + 5)
//=> [5, 6, 7, 8, 9, 10, 11, 12]

To fill sequencial characters, starting from 'G':

Array(8).fill().map((element, index) => String.fromCharCode('G'.charCodeAt(0) + index)) 
//=> ["G", "H", "I", "J", "K", "L", "M", "N"]

You can make your own re-usable function I suppose, for your example:

function makeArray(count, content) {
   var result = [];
   if(typeof content == "function") {
      for(var i = 0; i < count; i++) {
         result.push(content(i));
      }
   } else {
      for(var i = 0; i < count; i++) {
         result.push(content);
      }
   }
   return result;
}

Then you could do either of these:

var myArray = makeArray(8, 1);
//or something more complex, for example:
var myArray = makeArray(8, function(i) { return i * 3; });

You can give it a try here, note the above example doesn't rely on jQuery at all so you can use it without. You just don't gain anything from the library for something like this :)

for (var i=8, a=[]; i--;) a.push(1);

One liner:

new Array(10).fill(1).map( (_, i) => i+1 )

Yields:

[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]

Using Jquery:

---

$.map($(Array(8)),function(val, i) { return i; })

This returns:

[0, 1, 2, 3, 4, 5, 6, 7]

---

$.map($(Array(8)),function() { return 1; })

This returns:

[1, 1, 1, 1, 1, 1, 1, 1]

---

2016 - Modern Browser functionality has arrived. No need for jquery all the time.

Array.from({length: 8}, (el, index) => 1 /* or index */);

You can substitute the arrow function with a simple callback function to reach a slightly wider range of supported browsers. It's, for me at least, the easiest way to iterate over an initialized array in one step.

Note: IE is not supported in this solution, but there is a polyfill for that at developer.mozilla.org/...