removeAccent.js

function removeAccent(text) {

    /*
      Octal representation of letters
      Execute the above code at browser console to show octal number of the chars
      for(var i = 300; i < 380; i += 1, console.log(i + ' - ', String.fromCharCode(parseInt(i, 8)))) {}
    */
    var accent = [
      /[\300-\306]/g, /[\340-\346]/g, // A, a
      /[\310-\313]/g, /[\350-\353]/g, // E, e
      /[\314-\317]/g, /[\354-\357]/g, // I, i
      /[\322-\330]/g, /[\362-\370]/g, // O, o
      /[\331-\334]/g, /[\371-\374]/g, // U, u
      /[\321]/g, /[\361]/g, // N, n
      /[\307]/g, /[\347]/g, // C, c
    ];
    var chars = ['A', 'a', 'E', 'e', 'I', 'i', 'O', 'o', 'U', 'u', 'N', 'n', 'C', 'c'];

    for (var i = 0; i < accent.length; i++) {
      text = text.replace(accent[i], chars[i]);
    }

    return text;
  }

Usage:

removeAccent('ÁÉÍÓÚ âêìõú Ññ Çç');
> "AEIOU aeiou Nn Cc"