如何更改全局变量的值

Question

Default variable set var a = ''; var b = ''; var html =' <td>'+a+b+'</td>' var a = ''; var b = ''; var html =' <td>'+a+b+'</td>' var a = ''; var b = ''; var html =' <td>'+a+b+'</td>' ;

then I create another event use ajax

$('element').click(function(){
....

         //when ajax was success  change value of variable 
         a = 'webb';
         b = 'sam';
         // And append the variable "html"
         $(div).append(html );  

but the variable a & b is empty. why??

Answer 1

I think the problem is that you have assigned "html" variable value of "<td> + a + b + </td>" when a & b were empty and then never changed it. Try:

     a = 'webb';
     b = 'sam';
     // And append the variable "html"
     html =' <td>'+a+b+'</td>'
     $(div).append(html); 

Just to give some clarity: this is not related with variables being global or local. You get empty " <td></td> " because variable "html" is assigned a value (ie it get's normal string value rather than a reference to a and b variables).