阵列拼接删除阵列中的所有元素

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。这是否与toString方法有关？

注：我试图将字符串“9”添加到数组的中间，而不是从数组中删除任何东西。

Answer 1

在你的理解中缺失的环节是拼接的返回值，这是删除的项目。

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（在这种情况下无）中的项目，而不是剪接发生之后的阵列。

Answer 3

拼接不返回数组只是增加了它在现有的阵列：

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);