Array.prototype.indexOf = function(val) { 
for (var i = 0; i < this.length; i++) { 
if (this[i] == val) return i; 
} 
return -1; 
}; 

Array.prototype.remove = function(val) { 
var index = this.indexOf(val); 
if (index > -1) { 
this.splice(index, 1); 
} 
}; 

var emp = ['abs','dsf','sdf','fd'] 

emp.remove('fd'); 

//刪除起始下標(biāo)為1，長度為1的一個(gè)值(len設(shè)置1，如果為0，則數(shù)組不變) 
var arr = ['a','b','c','d']; 
arr.splice(1,1); 
console.log(arr); 
//['a','c','d']; 
//刪除起始下標(biāo)為1，長度為2的一個(gè)值(len設(shè)置2) 
var arr2 = ['a','b','c','d'] 
arr2.splice(1,2); 
console.log(arr2); 
//['a','d'] 

//替換起始下標(biāo)為1，長度為1的一個(gè)值為‘ttt'，len設(shè)置的1 
var arr = ['a','b','c','d']; 
arr.splice(1,1,'ttt'); 
console.log(arr); 
//['a','ttt','c','d'] 
var arr2 = ['a','b','c','d']; 
arr2.splice(1,2,'ttt'); 
console.log(arr2); 
//['a','ttt','d'] 替換起始下標(biāo)為1，長度為2的兩個(gè)值為‘ttt'，len設(shè)置的1 

var arr = ['a','b','c','d']; 
arr.splice(1,0,'ttt'); 
console.log(arr); 
//['a','ttt','b','c','d'] 表示在下標(biāo)為1處添加一項(xiàng)'ttt' 

var arr = ['a','b','c','d']; 
delete arr[1]; 
arr; 
//["a", undefined × 1, "c", "d"] 中間出現(xiàn)兩個(gè)逗號，數(shù)組長度不變，有一項(xiàng)為undefined