var iNum01 = 12;
var iNum02 = 24;
var sNum03 = '12';
var sTr = 'abc';
alert(iNum01+iNum02); //彈出36
alert(iNum01+sNum03); //彈出1212 數(shù)字和字符串相加等同于字符串相加
alert(sNum03+sTr);   // 彈出12abc

var sNum01 = '12';
var sNum02 = '24';
var sNum03 = '12.32';
alert(sNum01+sNum02); //彈出1224
alert(parseInt(sNum01)+parseInt(sNum02)) //彈出36
alert(sNum03)  //彈出數(shù)字12 將字符串小數(shù)轉(zhuǎn)化為數(shù)字整數(shù)

var sNum03 = '12.32'
alert(parseFloat(sNum03)); //彈出 12.32 將字符串小數(shù)轉(zhuǎn)化為數(shù)字小數(shù)

var sTr = '2017-4-22';
var aRr = sTr.split("-");
var aRr2= sTr.split("");
alert(aRr); //彈出['2017','4','2']
alert(aRr2); //彈出['2','0','1','7','-','4','-','2','2']

var sId = "#div1";
var sTr = sId.charAt(0);
alert(sTr); //彈出 #

var sTr = "abcdefgh";
var iNum = sTr.indexOf("c");
alert(iNum); //彈出2

var sTr = "abcdefghijkl";
var sTr2 = sTr.substring(3,5);
var sTr3 = sTr.substring(1);
alert(sTr2); //彈出 de
alert(sTr3); //彈出 bcdefghijkl

var sTr = "abcdef";
var sTr2 = sTr.toUpperCase();
alert(sTr2); //彈出ABCDEF

var sTr = "ABCDEF";
var sTr2 = sTr.toLowerCase();
alert(sTr2); //彈出abcdef

var str = 'asdfj12jlsdkf098';
var str2 = str.split('').reverse().join('');
alert(str2);