一句简单的JS写法求助

Question

可能我表达不清我是想达到这意思  其中n=1 n=2 n=3··········function tab(n){
document.form+n+.user+n+.focus();
}

Answer 1

//技术有限 方法比较笨点  function init(count_f,count_t){
var elemts = document.forms[count_f];
var _inputs =elemts.getElementsByTagName("input");
var j=0;
for(var i=0;i<_inputs.length;i++){
if(_inputs[i].getAttribute("type")=="text"){
  j++;
}
if(j == count_t){
inputs[i].focus();
}
}
}

Answer 2

eval('document.form'+n+'.user'+n+'.focus();'); 

Answer 3

eval('document.form'+n+'.user'+n+'.focus();'); 

Answer 4

eval("document.forms['form"+n+"'].user"+n+".focus()");