<script type="text/javascript">
var a='3';
var b='4';
document.write('<br>'+a*b);//12
document.write('<br>'+a+b+'<br>');//34..注意這裡是字串相加
document.write(Number(a)+Number(b));//7
document.write('<br>');
document.write(+a + +b);//7
document.write('<br>');
var age = '20 year';
var age2= '08 year';
document.write(parseInt(age,10));//20
document.write('<br>');
document.write(parseInt(age2));//0
document.write('<br>');
document.write(parseInt(age2,10));//08
document.write('<br>');
//isNan(a) a是否非數值形
//四捨五入Math.round(n);向上舍入Math.ceil(n);向下舍入Math.floor(n);
</script>
<script type="text/javascript">
var arrylist = [1,'a',true];
arrylist.push('b','c');//pop()
arrylist.unshift('head');//shift()
//splice可增減改
//刪splice(1,2);插splice(2,0,'splice_insert');換splice(2,1,'splice_replace');
var my_string = 'asd qwe zcx asd er qw ad';
//toUpperCase();tolowerCase();length;indexOf('');lastIndexOf('');slice(n);slice(n,m);search(regex);replact(regex,'replaceString');
document.write('<br>');
var people = ['ron','sally','tricia','bob'];
var random = Math.floor(Math.random()*people.length);
document.write(people[random]);
document.write('<br>');
</script>