Simple js FOR loop returning 'undefined'

for-loop, javascript, variables

Solution

In JavaScript, if a variable is not initialized explicitly, it will by default have `undefined`. That is not a string but a primitive type of the Language. You can check that by printing it

var newStr;
console.log(newStr);
// undefined
console.log(newStr + "thefourtheye");
// undefinedthefourtheye

So, just initialize the variable with an empty string, like this

var newStr = '';

Also, note that, in this line

for(i=0; i < x.length; i++) {

`i` has never been declared before. So, a new global variable `i` will be created. You may not want that. So, just use `var` keyword to declare the variable scoped to the current function, like this

for (var i = 0; i < x.length; i++) {

Apart from that, `translate2` is a function and when it is invoked, one would expect it to return something. But you are not returning anything explicitly. So, again, JavaScript, by default, returns `undefined`. That is why you are getting the second `undefined` in the question. To fix that, use `return` statement like this

function translate2(x) {
    var newStr = "";
    for (var i = 0; i < x.length; i++) {
        newStr += x.charAt(i);
    }
    return newStr;
}

Problem

Not sure what I'm doing wrong here; the variable `newStr` should just return "Hello World", but I'm getting this instead: ``` "undefinedHello World" undefined ``` JS ``` function translate2(x){ var newStr; x = "Hello World"; for(i=0; i<x.length; i++) { newStr+=x.charAt(i); } console.log(newStr); } ```

Original source