添加特定的数组值

Question

Ok, so I have an array.

var array = ['159','350','317','350','138','163','317','367','352','317'];

I want to loop through the array and take only specific values each time the loop runs and put these into another array. Eg taking every 3rd item in the array, so....

var a = 3;
var colArray = [];

for (var i = 0; i < a; i++) {
  colArray[i] = [];
  for (var k = i; k < array.length; k += a) {
     colArray[i].push(array[k]);
  };    
}; 

console.log(colArray);

....would give this in the console on the first iteration.....

159, 350, 317, 317

All that works fine, but want I then want to do is add up the values in each array of colArray . I DON'T want the total of each array, but want the 1st value to be added to 0, the 2nd to 0 + 1st and so on, to give something like this....

159, 509, 826, 1143 

jsFiddle

Answer 1

I think this is what you want, there is probably a better way to do it, but this worked for me.

  var array = ['159','350','317','350','138','163','317','367','352','317','159','138'];

var a = 3;
    var colArray = [];
    for (var i = 0; i < a; i++) {
      colArray[i] = [];

      for (var k = i; k < array.length; k += a) {
        if(k<a){
         colArray[i].push(Number(array[k]));
        }else{
         colArray[i].push(Number(array[k]) + Number(colArray[i][(k-a-i)/a]));
        }
      };    
    }; 

    console.log(colArray);