javascript - 多次查找数组中相同元素的索引

Question

我想在同一个数组中找到一个元素的POSITIONS，没有方法，有一个算法...

示例:

var a = [1,2,2,1,4,5,6]
to display positions of 1 : position 0 and 3
to display positions of 2 : position 1 and 2

到目前为止我做了什么:

function count(array,element){
    while(element in array){
        return array.indexOf(element);
    }
}

Answer 1

为了得到所有的位置，你必须在返回之前遍历整个数组

var a = [1,2,2,1,4,5,6]

function count(array,element){
  var counts = [];
    for (i = 0; i < array.length; i++){
      if (array[i] === element) {  
        counts.push(i);
      }
    }
  return counts;
}

count(a, 1); //returns [0,3]
count(a, 2); //returns [1,2]