萌新求教（

Emmm......
昨天才接触js，，
求教一下为什么function里面的for语句执行时会略过，这是js的特性吗，有没有什么办法解决
代码如下：
 wi.b.click(function(){  
 threads.start(function(){
var aqwe = "qwertyuiop";
var asqwe = "QWERTYUIOP";
var bqwe = "asdfghjkl";
var bsqwe = "ASDFGHJKL"
var cqwe = "zxcvbnm";
var csqwe = "ZXCVBNM";
var str = wi.trb.getText();
    var runul = "";
    for (var i = 0; i < str.length; i++) {
        var code = str.substring(i,i+1);
        var lstuna = aqwe.indexOf(code)-1;
        var lstunas = asqwe.indexOf(code)-1;
        var lstunb = bqwe.indexOf(code)-1;
        var lstunbs = bsqwe.indexOf(code)-1;
        var lstunc = cqwe.indexOf(code)-1;
        var lstuncs = csqwe.indexOf(code)-1;
        
        if (lstuna+1!=-1){
                if (lstuna+1!=0){
                    var code=(aqwe.substring(lstuna-1,lstuna));
                    }else if(lstuna+1==0){
                        lstuna = lstuna+10;
                        var code=(aqwe.substring(lstuna-1,lstuna));
            }};
            
            if (lstunas+1!=-1){
                if (lstunas+1!=0){
                    var code=(asqwe.substring(lstunas-1,lstunas));
                    }else if(lstunas+1==0){
                        lstunas = lstunas+10;
                        var code=(asqwe.substring(lstunas-1,lstunas));
            }};
            
        if (lstunb+1!=-1){
                if (lstunb+1!=0){
                    var code=(bqwe.substring(lstunb-1,lstunb));
                    }else if(lstunb+1==0){
                        lstunb = lstunb+10;
                        var code=(bqwe.substring(lstunb-1,lstunb));
            }};
            
            if (lstunbs+1!=-1){
                if (lstunbs+1!=0){
                    var code=(bsqwe.substring(lstunbs-1,lstunbs));
                    }else if(lstunbs+1==0){
                        lstunbs = lstunbs+10;
                        var code=(bsqwe.substring(lstunbs-1,lstunbs));
            }};
            
        if (lstunc+1!=-1){
                if (lstunc+1!=0){
                    var code=(cqwe.substring(lstunc-1,lstunc));
                    }else if(lstunc+1==0){
                        lstunc = lstunc+8;
                        var code=(cqwe.substring(lstunc-1,lstunc));
            }};
            
            if (lstuncs+1!=-1){
                if (lstuncs+1!=0){
                    var code=(csqwe.substring(lstuncs-1,lstuncs));
                    }else if(lstuncs+1==0){
                        lstuncs = lstuncs+8;
                        var code=(csqwe.substring(lstuncs-1,lstuncs));
            }};
            
        runul+=code;
        alert(runul);
            };
  alert(runul);     
 });
});
 第一个alert没有执行，尝试在for循环内的任意位置添加alert/toast，均无效