Question

this is a function to call SELECT element values. but i am facing an error.
code is here.

function get_s_val(){
var foo = all_categories_1;
var ov1 = "";

    for(m=0;m<=foo.length;m++){
        ov1 += foo[m].value+',';
    }

console.log(ov1);
var tme=setTimeout("get_s_val()", 1000);
}
get_s_val();

it shows an error like "Uncaught TypeError: Cannot read property 'value' of undefined"

but when i do some littel changes it works.. like

function get_s_val(){
var foo = all_categories_1;
var ov1 = "";

    //for(m=0;m<=foo.length;m++){
        ov1 += foo[0].value+',';
    //}

console.log(ov1);
var tme=setTimeout("get_s_val()", 1000);
}
get_s_val();

i dont know that where i am wrong to write the code.

Answer 1

Modify your loop condition to run while the iterator is less than the length of the array, or you’ll get undefined when you hit the non-existent element at index foo.length:

for(var m=0;m<foo.length;m++){
    ov1 += foo[m].value+',';
}

…and always declare variables with the var keyword, or bad things will happen, and JSLint will whine about it (and rightly so, but that’s another topic).