map
,filter
,every
,some
方法,我們分別進(jìn)行舉例//map定義一個(gè)函數(shù)用來(lái)遍歷原來(lái)老的數(shù)組 var arr = [10,20,5,1000,50]; var newArr = arr.map(function(value, index, array){ return value>10 && value*2 ;//value大于10的時(shí)候才會(huì)乘2 }); console.log(newArr); //filter()定義一會(huì)判斷條件然后把滿足要求的數(shù)組選出來(lái) var arr2 = [1,2,3,4,5,6,7,8]; var newArr2 = arr2.filter(function (value,index,array) { return index%2 == 0 || value >5; }); console.log(newArr2); //every()定義一個(gè)判斷條件,然后返回是不是每個(gè)值都都滿足判斷條件 var arr3 = [11,2,3,4,15]; var newArr3 = arr3.every(function (value, index) { return value>1; }); console.log(newArr3); //some()定義一個(gè)判斷條件,然后返回是不是存在一個(gè)值都都滿足判斷條件 var arr4 = [11,2,3,4,15]; var newArr4 = arr4.some(function (value, index) { return value>100; }); console.log(newArr4);
運(yùn)行結(jié)果
//1.圓周率 console.log(Math.PI); //2.向上取整數(shù)ceil,向下取整數(shù)floor console.log(Math.ceil(Math.PI)); console.log(Math.floor(Math.PI)); //3.取整數(shù),四舍五入 console.log(Math.round(3.4)); console.log(Math.round(3.5)); console.log("======================="); //4.取絕對(duì)值 console.log(Math.abs(-3)); console.log(Math.abs(4)); //5.求最大值和最小值 console.log(Math.min(8,245,52,58,2,45,45)); console.log(Math.max(4,5,8,7,6,4)); console.log("=======================") //6.生成隨機(jī)數(shù) console.log(Math.random())//0-1之間的隨機(jī)數(shù) console.log(Math.random()*10)//0-10之間的隨機(jī)數(shù) //假如我們想要3-8之間的隨機(jī)數(shù),我們應(yīng)該怎么辦 //有一個(gè)公式 Math.random() * (y - x) + x //比如我們想要5-9之間的隨機(jī)數(shù),那么就是 console.log(Math.random() * (9 - 5) + 5); //7.正余弦 console.log(Math.sin(Math.PI / 2)); console.log(Math.cos(Math.PI / 2));//得到的數(shù)值已經(jīng)接近0了 //8.求指數(shù)冪pow(),求平方根 console.log(Math.pow(5, 4)); console.log(Math.sqrt(4));
運(yùn)行結(jié)果:
//靜態(tài)成員 var LKTool = { height:function(){ } }; console.log(LKTool.height); //實(shí)例成員 function Dog(name,sex){ this.name = name; this.sex = sex; } var dog = new Dog("xiaoming","male"); console.log(dog.name);
運(yùn)行結(jié)果
https://github.com/ruigege66/JavaScript/blob/master/D22_1_AddedMethod.html
https://github.com/ruigege66/JavaScript/blob/master/D22_2_MathObject.html
https://www.cnblogs.com/ruigege0000/
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