How to NOT show Undefined when not assign value-CodePudding

I have this function in JavaScript

function person(settings) {
  console.log(settings.name);
  console.log(settings.age);
}

And I assigned value to the function :

function({
  name: `Nana`,
});

The result are

Nana
Undefined

I just want to skip to assign value to age and also I don't want to get undefined I want to get the result only Nana

What should I do?

CodePudding user response：

<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
<script>
function person(settings) {
 result = '';
   if(settings.name!=undefined) {
    result  = settings.name;
    }
    result  = ' ';
   if(settings.age!=undefined) {
        result =settings.age;
    }

    
    alert(result);
}
</script>
</head>
<body>

<h1>This is a Heading</h1>
<p onclick="person({
  name: `Nana`
});">Click Here</p>

</body>
</html>

how to and test video

CodePudding user response：

Your function print both, so you see the undefined one. You can use if statement to print only if it is not undefined.

function person(settings) {
   if (settings.name != undefined) console.log(settings.name); 
   if (settings.age != undefined) console.log(settings.age);
}

also you can use:

function person(settings) {
   if (settings.name) console.log(settings.name); 
   if (settings.age) console.log(settings.age);
}

this work because any javascript value can be convert to a boolean value, and the folowing values convert to 'false':

undefined
null
0
-0
NaN
""  // the empty string