function splice(arr, index, del) {
	function 
	if (del > 0) {
		var arr2 = [];
		for (i = 0; i < index; i++) {
			arr2[i] = arr[i];
		}
		var value = [];
		for (i = index + del; i > index && i < arr.length; i++) {
			value[value.length] = arr[i];
		}

		
	} else if (arguments.length > 3) {
		for (k = (index + 1); k < arguments.length; k++) {
			arr[arr.length] = arguments[k];
		}
		for (j = 0; j < value.length; j++) {
			arr[arr.length] = value[j];
		}
		return arr;
	}

		return arr2;
		return value;

}

var arr = [1, 2, 4, 3, 8, 7];
arr = splice(arr, 2, 1);
console.log(arr); // [1, 2, 3]
arr = splice(arr, 2, 0, 100, 200, 300);
console.log(arr); // [1, 2, 100, 200, 300, 3]