js中splice的刪除、截取、插入、替換

var arr =["George","John","Thomas","James","Adrew","Martin"]

let mm = arr.splice(2,3)

console.log(arr)  //  結果  ["George","John","Martin"]    如果arr不賦給某個值，直接使用arr.splice(2,3) ，結果arr就是刪除第三位后面的三個元素之后剩余元素組成的數組

console.log(mm)   //  結果  ["Thomas","James","Adrew"]   如果arr賦給某個值，結果mm就是第三位元素后面的三個元素組成的數組。

 

var arr1 =["George","John","Thomas","James","Adrew","Martin"]   

arr1.splice(2,0,"Jack")   [ "George", "John", "Jack", "Thomas", "James", "Adrew", "Martin" ]  // 插入  將新元素插入第三個位置，后面的依次排后

arr1.splice(2,1,"Jack")   [ "George", "John", "Jack", "James", "Adrew", "Martin" ] // 替換    將新元素替換掉第三個元素