Angular. how not to repeat the same function

Question

This function works, but how It would be possible avoid typing the same for loop for a second variable and somehow use only one. Trying to Don't repeat yuorself method here. Do I need to use an array?

JS:

var app=angular.module('xpCalc', []);
app.controller('xpCalculatorController', function($scope){
$scope.currentLevel=1;
$scope.currentXp=function(){
    var output=0;
    for (var thisLVL=1; thisLVL < $scope.currentLevel; thisLVL++) {
        output += ( Math.floor ( thisLVL + 300 * Math.pow( 2, thisLVL / 7 ) ) / 4 );
    }
    return output;
  };
  $scope.desiredLevel=1;
  $scope.desiredXp=function(){
    var output=0;
    for (var thisLVL=1; thisLVL < $scope.desiredLevel; thisLVL++) {
        output += ( Math.floor ( thisLVL + 300 * Math.pow( 2, thisLVL / 7 ) ) / 4 );
    }
    return output;
  };
});

HTML:

<h2>{{desiredXp()-currentXp()}}</h2>

First off, calculate desiredXp()-currentXp() in controller or service. After post result in HTML. Further, use :: bindOnce, for example <h2>{{::result}}</h2>. Anyways its not good practice to use function in HTML, you call it every digest cycle — Maxim Shoustin
– Maxim Shoustin, Commented Aug 26, 2016 at 7:57

Vermicello · Accepted Answer · 2016-08-26 08:00:37Z

1

Try this.

var app=angular.module('xpCalc', []);
app.controller('xpCalculatorController', function($scope){
$scope.currentLevel=1;
$scope.currentXp=InternalLoop($scope.currentLevel);
$scope.desiredLevel=1;
$scope.desiredXp=InternalLoop($scope.desiredLevel);

function InternalLoop(level){
    var output=0;
    for (var thisLVL=1; thisLVL < level; thisLVL++) {
        output += ( Math.floor ( thisLVL + 300 * Math.pow( 2, thisLVL / 7 ) ) / 4 );
    }
    return output;
  };

});

answered Aug 26, 2016 at 8:00

Vermicello

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1 Comment

vp_arth Over a year ago

You also should add $watch for input variables.

Shiva Prasad · Accepted Answer · 2016-08-26 08:11:18Z

0

You can try this:

var app=angular.module('xpCalc', []);
app.controller('xpCalculatorController', function($scope){
$scope.currentLevel=1;
var getResult = function(level)
{
   var output=0;
   for (var thisLVL=1; thisLVL < level; thisLVL++) {
     output += (Math.floor(thisLVL+300*Math.pow(2,thisLVL/7))/4);
   }
   return output;
}
$scope.currentXp=getResult($scope.currentLevel);
$scope.desiredLevel=1;
$scope.desiredXp=getResult($scope.desiredLevel);
});

answered Aug 26, 2016 at 8:11

Shiva Prasad

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Comments

vp_arth · Accepted Answer · 2016-08-26 08:20:53Z

Task:

xp = sum[floor(i + 300*2^(i/7)) / 4], i = 1..level
4*xp = sum[i] + sum[floor(300*2^(i/7))], i = 1..level
4*xp = level*(level+1)/2 + sum[floor(300*2^(i/7))], i = [1..level)

We come to next function:

function getXP(level) {
  var xp = level*(level+1)/2, i;
  var sum = 0;
  for (i = 1; i < level; i++)
    sum+=Math.floor(300 * Math.pow(2, i/7));
  return (xp + sum) / 4;
}

However, getXP(5) - getXP(3) will equal like we skip first 3 steps

function getXP(to, from) {
  from = from || 1;
  var xp = 0, i;
  for (i = from; i < level; i++)
    sum += i + Math.floor(300 * Math.pow(2, i/7));
  return xp / 4;
}

So, you can now use it like {{getXP(desiredLevel, currentLevel)}}

This function will be called each digest iteration. It's bad.

You have at least two options to deal with it:

Calculate result in your controller and watch about arguments to recalc it.
Memoize your function

Something like this:

var hash = {};
function mgetXP(to, from) {
  if (typeof hash[key(to, from)] != 'undefined') return hash[key(to, from)];
  return hash[key(to, from)] = getXP(to, from);
  function key(to, from) {return [to, from].join('_'); }
}

Dhananjaya Kuppu · Accepted Answer · 2016-08-26 08:41:11Z

0

You may also try this approach:

$scope.currentLevel=1;
$scope.currentXp = xp($scope.currentLevel);
$scope.desiredLevel=1;
$scope.desiredXp = xp($scope.desiredLevel);

function xp(level) {    
   function calc(index, result){
      if (index >= level) return result;
      result += (Math.floor( index + 300 * Math.pow( 2, index / 7 ) ) / 4);
      return calc(index + 1, result);
   }
   return calc(1, 0);    
}

answered Aug 26, 2016 at 8:41

Dhananjaya Kuppu

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