0513JS数组内置方法、数学函数、时间函数

|数组中常用的内置方法
|-push()与pop()
|--push()是往数组的尾部添加，同时返回新数组的长度

var attr = [1,2,3,4,5];
var attr2 = [6,7,8,9,0];
var get = attr.push(attr2);
console.log(attr);
console.log(get);

            
|--pop()是删除数组的最后一项，同时给我返回删除的这一项

var attr = [1,2,3,4,5];
var get = attr.pop();
console.log(attr);
console.log(get);

|-unshift()与shift()
|--unshift()是往数组的头部添加，同时返回新数组的长度

var attr = [1,2,3,4,5];
var get = attr.unshift(10);
console.log(attr);
console.log(get);

|--shift()是删除数组的第一项，同时给我返回删除的这一项

var attr = [1,2,3,4,5];
var get = attr.shift();
console.log(attr);
console.log(get);

|-reverse()对数组中的项进行反转

var attr = [1,2,3,4,5];
var get = attr.reverse();
console.log(attr);
console.log(get);

|-concat()在数组的尾部添加新项

var attr1 = [1,2,3,4,5];
var attr2 = [6,7,8,9,0];
var get = attr1.concat(attr2);
var get1 = attr1.concat("和" , attr2);
var get2 = attr1.concat("和" + attr2);
console.log(get);
console.log(get1);
console.log(get2);

|-indexOf()与lastindexOf()
|--indexOf()返回数组中第一次出现所查项的索引,如果没有,返回-1

var attr = [4,1,66,4,23,2];
var get = attr.indexOf(66);
var get = attr.indexOf(55);
console.log(attr);
console.log(get);

|--laseindexOf()返回数组中第一次出现所查项的索引，如果没有，返回-1

var attr = [4,1,66,4,23,2,66];
var get = attr.lastIndexOf(66);
var get = attr.lastIndexOf(55);
console.log(attr);
console.log(get);

|数学函数  Math
|-Math.random 随机数  在0~1之间的,0能取到,1取不到

vvar attr = Math.random();
var attr = parseInt(Math.random()*100);
console.log(attr)

|-Math.max、Math.min 最大值、最小值

Math.max、Math.min 最大值、最小值
var attr = Math.max(1,6,8,2);
var attr = Math.min(1,6,8,2);
console.log(attr);

|-Math.PI 圆周率

var attr = Math.PI;
console.log(attr);

|时间函数
|-var mydate = new Date();

var date = new Date();
var year = date.getFullYear();
var month = date.getMonth()+1;
var day = date.getDate();
var hour = date.getHours();
var minutes = date.getMinutes()
var seconds = date.getSeconds();
document.write(year + "-" + month + "-" + day + "&nbsp;" + hour + ":" + minutes + ":" + seconds + "<br />");
document.write(date.toLocaleDateString() + "<br />");
document.write(date.toLocaleTimeString() + "<br />");
document.write(date.toLocaleString());