数组拼接从数组中删除所有元素

Question

var currentAge = 26;
var maxAge = 100;
var amountPerDay = 30.50;
var calculation = (((maxAge - currentAge) * 365) * amountPerDay);
console.log(calculation);
var stringCalc = calculation.toString().split('').splice(2, 0, "9");
console.log(stringCalc);

console.log（stringCalc） 显示一个空数组。这与 toString 方法有关吗？

注意：我正在尝试将字符串"9"添加到数组的中间，而不是从数组中删除任何内容。

Answer 1

理解中缺少的环节是拼接的返回值，即已删除的项目。

var currentAge = 26;
var maxAge = 100;
var amountPerDay = 30.50;
var calculation = (((maxAge - currentAge) * 365) * amountPerDay);
console.log(calculation);
var stringCalc = calculation.toString().split('');
console.log(stringCalc);
// ["8", "2", "3", "8", "0", "5"]
console.log(stringCalc.splice(2, 0, "foo"));
// [] because no items were deleted, return value = array of deleted items
console.log(stringCalc)
// ["8", "2", "foo", 3", "8", "0", "5"]

Answer 2

var currentAge = 26;
var maxAge = 100;
var amountPerDay = 30.50;
var calculation = (((maxAge - currentAge) * 365) * amountPerDay);
console.log(calculation);
var stringCalc = calculation.toString().split('');
console.log(stringCalc);
stringCalc.splice(2, 0, "9");
console.log(stringCalc);

splice()返回取出的项（在本例中为 none），而不是拼接发生后的数组。

Answer 3

> splice 不返回数组，只是将其添加到现有数组中：

var currentAge = 26;
var maxAge = 100;
var amountPerDay = 30.50;
var calculation = (((maxAge - currentAge) * 365) * amountPerDay);
var numberArray = calculation.toString().split('')
numberArray.splice(2, 0, "9");
console.log(numberArray);