Javascript passing variable in function

Question

I am new to javascript. I am creating a text adventure. I am trying to write a function to take a given parameter, and use the .toLowerCase and return it as the same variable. I think I have the general idea to do it, but I just can not get it to work. Thanks!

function lowercase(a){
    return a.toLowerCase();
}

var alive = 1;
while(alive == 1){
    var name = prompt("What is your name?");
    lowercase(name);
    document.write("Hello " + name + "!\n");
    break;
}

Strings are **immutable**. Every method that changes a string value in any way returns a *new* string. — Felix Kling, Feb 28 '15 at 01:30
Why are you running a `while` loop and then breaking out of it straight away? — Qantas 94 Heavy, Feb 28 '15 at 01:48

score 1 · Answer 1 · answered Feb 28 '15 at 00:23

1

You need to assign the result of the function:

name = lowercase(name);

Are you new to programming in general? Because Javascript is similar to most other language in this regard.

answered Feb 28 '15 at 00:23

Barmar

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Also, you can skip `lowercase(a)` completely and just do this: `name = name.toLowerCase()`. – Dai Feb 28 '15 at 00:24
@Dai Of course, but it seems like he's trying to learn how to write and use functions. – Barmar Feb 28 '15 at 00:25
Yes @Dia. I do realize how to use .toLowerCase, but I want to learn how to use them. – Feb 28 '15 at 00:31

score 1 · Answer 2 · edited May 23 '17 at 12:22

1

name = lowercase(name);

Since you are returning the value in your function, you must reinitialize the value of the variable. Javascript as far as I know is not a "pass by reference" language. It has always been a "pass by value". Read more about it here.

What's the difference between passing by reference vs. passing by value?

edited May 23 '17 at 12:22

Community

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answered Feb 28 '15 at 00:38

kapitanluffy

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score 0 · Answer 3 · answered Feb 28 '15 at 00:23

The value of the name variable isn't being changed at the moment, you need to assign it to the result of the function.

function lowercase(a){
    return a.toLowerCase();
}

var alive = 1;
while(alive == 1){
    var name = prompt("What is your name?");
    name = lowercase(name);
    document.write("Hello " + name + "!\n");
    break;
}

qwerty_igor · Accepted Answer · 2015-06-12T06:39:19.193

0

use name = lowercase(name); the function returns a result, but you have to assign this result to a variable in order to use it after, or you can simply say

document.write('Hello' + lowercase(name) + 'something');

edited Jun 12 '15 at 06:39

answered Feb 28 '15 at 00:24

qwerty_igor

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score 0 · Answer 5 · answered Feb 28 '15 at 00:27

name = lowercase(name);

Note, you should almost always use "===" instead of "==". "===" tests whether something's value and data type (number, string, boolean, object, etc.) matches another, whereas "==" only tests whether the values match (after performing a type conversion). For example:

if ("42" == 42) { // true (string 42 equals number 42)
if ("42" === 42) { // false (string does not equal number, what you want)

Javascript passing variable in function

5 Answers5