Split array of objects

chunk.js

/**
 * Split array
 * @param arr[] The array to split
 * @param startFn Start condition
 * @param endFn End condition
 */
function chunk(arr, startFn, endFn) {
    var chunks = [];

    var chunk = [];
    for (let elem of arr) {
        if (startFn(elem)) {
            chunk = [];
        }

        chunk.push(elem);

        if (endFn(elem)) {
            chunks.push(chunk);
            chunk = [];
        }
    }

    return chunks;
}

var arr = [
  {
  	id: 23,
    source: "a"
  },
  {
  	id: 32,
    source: "b"
  },
  {
  	id: 42,
    source: "c"
  },
  {
  	id: 13,
    source: "a"
  },
  {
  	id: 12,
    source: "d"
  },
  {
  	id: 14,
    source: "c"
  }
];

var ans = chunk(arr, (e) => e.source === "a", (e) => e.source === "c");
console.log(ans);