js数组常用api

求和:

Array.prototype.sum = function (){
	return this.reduce((partial, value)=>{
		return parseInt(partial) + parseInt(value);
	})
};
console.log(["1",1,2].sum())

根据条件过滤:

var arr = [
  {"name":"apple","count":2},
  {"name":"orange","count":5},
  {"name":"pear","count": 3},
  {"name":"orange","count": 16},
];
   
var newArr = arr.filter(function(item){
  return item.name === "orange"&&item.count==5;
});

根据条件增加删除新元素:

var oldArr = [{
	first_name:"Colin",last_name:"Toh"}
			  ,{
				  first_name:"Addy",last_name:"Osmani"}
			  ,{
				  first_name:"Yehuda",last_name:"Katz"}
			 ];
function getNewArr(){
	return oldArr.map(function(item,index){
		item.newName = [item.first_name,item.last_name].join(" ");
		return item;
	}
	);
}




console.log(getNewArr());

根据条件增加删除新元素:

every()与some()方法都是JS中数组的迭代方法。every()是对数组中的每一项运行给定函数，如果该函数对每一项返回true,则返回true。some()是对数组中每一项运行指定函数，如果该函数对任一项返回true，则返回true。

　　

var arr = [{id:1,name:"语文"},{id:2,name:"数学"},{id:3,name:"政治"}];  
  
console.log( arr.some(function(item,index, array ){  
return item.id===1||item.id===2;  
}));

console.log(arr.every( function( item, index, array ){  
return item.id===1||item.id===2||item.id===3;  
}));