Question

I have a certain object created like this:

var classes = {

        login: {
            form: {
                wrapper:        'content-login',
                cls:            'login-form',
                fields:         'login-fields'
            },
            username: {
                wrapper:        'username-wrapper',
                label:          'user-img',
                input:          'username'
            },
            password: {
                wrapper:        'password-wrapper',
                label:          'pass-img',
                input:          'password'
            },
            button: {
                wrapper:        'login-wrapper',
                proceed:        'login'
            },
            toogle: {
                trigger: {
                    wrapper:    'toogle-button',
                    button:     'toogle'
                },
                buttons: {
                    wrapper:    'toogle-buttons',
                    twitter:    'twitter-login',
                    register:   'register',
                    recover:    'recover-password'
                }
            }   
        },

        register: {
            form: {
                wrapper:        'content-register',
                cls:            'register-form',
                fields:         'register-fields'
            },
            username: {
                wrapper:        'username-wrapper',
                label:          'username-label',
                input:          'username'
            },
            email: {
                wrapper:        'email-wrapper',
                label:          'email-label',
                input:          'email' 
            },
            password: {
                wrapper:        'password-wrapper',
                label:          'password-label',
                input:          'password'  
            },
            confirm: {
                wrapper:        'confirm-wrapper',
                label:          'confirm-label',
                input:          'confirm'
            },
            captcha: {
                wrapper:        'captcha-wrapper',
                label:          'captcha-label',
                input:          'captcha'
            },
            button: {
                wrapper:        'register-wrapper',
                message:        'message-handling',
                proceed:        'register'
            },
            back: {
                wrapper:        'back-button',
                button:         'back'
            }
        },

        recover: {
            form: {
                wrapper:        'content-recover',
                cls:            'recover-form',
                fields:         'recover-fields'
            },
            email: {
                wrapper:        'email-wrapper',
                label:          'email-label',
                input:          'email' 
            },
            button: {
                wrapper:        'recover-wrapper',
                proceed:        'recover'
            },
            back: {
                wrapper:        'back-button',
                button:         'back'
            }
        },

        reset: {
            form: {
                wrapper:        'content-reset',
                cls:            'reset-form',
                fields:         'reset-fields'
            },
            email: {
                wrapper:        'email-wrapper',
                label:          'email-label',
                input:          'email'
            },
            authcode: {
                wrapper:        'authcode-wrapper',
                label:          'authcode-label',
                input:          'authcode'  
            },
            password: {
                wrapper:        'password-wrapper',
                label:          'password-label',
                input:          'password'  
            },
            confirm: {
                wrapper:        'confirm-wrapper',
                label:          'confirm-label',
                input:          'confirm'
            },
            button: {
                wrapper:        'proceed-wrapper',
                message:        'message-handling',
                proceed:        'proceed'
            },
            back: {
                wrapper:        'back-button',
                button:         'back'
            }
        },

        success: {
            wrapper:            'after-login',
            message:            'row-one',
            buttons: {
                wrapper:        'row-two',
                cancel:         'cancel',
                proceed:        'continue'  
            }
        },

        lockdown: {
            wrapper:            'system-lockdown',
            message:            'row-one',
            buttons: {
                wrapper:        'row-two',
                back:           'back'
            }
        }

    }

And I’m trying to call a certain key like this:

classes[login.form.wrapper];

But it doesn’t work that way, only like this:

classes.login.form.wrapper;

Or like this:

classes['login'];

Can someone tell me why it doesn’t work like this :

classes[login.form.wrapper];

And can I make it work like that ? Because I have seen this method somewhere but I don’t know if it is the same thing I have.

Answer 1

classes[login.form.wrapper]; is looking for an object named login in whatever scope the line of code runs in. That won’t be found, because login is a property of classes. This will therefore throw a ReferenceError, because login is undefined.

If login was defined, and had a property named form which in turn had a property named wrapper, the value of that property would be used:

var login = {
        form: {
            wrapper: 'login'
        }
    };
console.log(classes[login.form.wrapper]); //Now this would return classes.login

classes.login.form.wrapper; works, because classes is an object with a property named login.

classes['login']; is equivalent to classes.login. You could write classes['login']['form']['wrapper'] as an equivalent to classes.login.form.wrapper.