> For the complete documentation index, see [llms.txt](https://book.tml.ink/app-development/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.tml.ink/app-development/backend-solution/overview.md).

# overview

## HTML code

Only need reference two Javascript Libraries in HTML:

```markup
<script src="https://TML.ink/X.tml"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.1.1/socket.io.js"></script>
```

The first line reference the client function library. This's a dynamic library includes many dynamic components and CDN resources, so don't save to local. For new features, *strongly* recommend above address which comes with the latest version of X-Server, many new components, enhanced performance, and more. The second line is using third-party socket library from CDN.

## Javascript code

### Create a client instance

```java
tim = TML('wss://x.TML.ink'); //Create a client instance
```

If you connect multiple servers at the same time, you can create multiple client instances. Connect a server,Load authentication module, Provide offline login codes and method, logout codes and method, multi-server login, automatic login, user cache and other functions of authentication. If you don't need these features, you should not execute this line of code.

### Using eXtend feature

```javascript
tim.X('feature name').xxx()
```

Feature name can be defined by yourself, starting with lowercase letter and only letters without numbers & symbols.\
.xxx() should be Get(), Set(), New(), Del(). These are all asynchronous methods, so every asynchronous method needs to be followed by "then" or add "await" in front.

```javascript
console.log(await tim.X('feature name').Get());//add "await" in front
```

Above codes can also be written as follow:

```javascript
tim.X('feature name').Get().then(data => console.log(data)); //followed by "then"
```

### Sign Up a new user

```javascript
tim.X('user').New({
   email: "test email",
   password: "test"
     });
```

### Login code

```javascript
tim.Login({
     email: "test email",
     password: "test"
   });
```

Use local cache to automatically login can be written as follow:

```javascript
tim.Login();
```

### Logout code

```javascript
tim.Logout();
```

### Monitor user registration

```javascript
tim.X('user').on('add', function(msg){
   console.log(msg);
      });
```

Listen for real-time messages registered by users. This will be a mass message to update other users' interfaces without refreshing.

### Get example

```javascript
console.log(await tim.X('user').Get());//Get top 10 users

//Get top 50 users
 console.log(await tim.X('user').Get({
   $max: 50
     }))

//Get the user whose email is 'a'
 console.log(await tim.X('user').Get({
   email: 'a'
 }))
```

Above codes are equivalent to:

```javascript
tim.X('user').Get().then(data => console.log(data));//Get top 10 users

//Get top 50 users
  tim.X('user').Get({
      $max: 50
     }).then(data => console.log(data));

//Get the user whose email is 'a'
  tim.X('user').Get({
   email: 'a'
     }).then(data => console.log(data));
```

## Operators of Get Method

### Equals a Specified Value

Specifies equality condition. The $eq operator matches documents where the value of a field equals the specified value. The following example queries the user collection to select all documents where the value of the email field equals a:

```javascript
tim.X('user').Get({
email: 'a'
}).then(data => console.log(data));
```

### $max

The $max stage has the following prototype form:

```javascript
{ $max: <positive integer> }
```

$max takes a positive integer that specifies the maximum number of documents to pass along. Consider the following example:

```javascript
tim.X('user').Get({
 $max: 50
}).then(data => console.log(data));
```

This operation returns only the first 50 documents. $max has no effect on the content of the documents it passes. Set $max to 0 will get the counting faster.

### $sort

Specifies the order in which the returns matching documents. You can apply $sort to sort by and a value of 1 or -1 to specify an ascending or descending sort respectively before retrieving any documents from the database. The following sample document specifies a descending sort by the \_time field and will returns the 10 newest documents:

```javascript
tim.X('user').Get({
$max: 10,
$sort: {
      _time: -1
    }
}).then(data => console.log(data));
```

This operation use $max in conjunction with $sort to return the first (in terms of the sort order) documents.

### lessThan

$lt selects the documents where the value of the field is less than (i.e. <) the specified value.

```javascript
tim.X('user').Get({
price: {
  $lt: 9.9
  }
});
```

## Catch an exception

Use try...catch statement marks a block of statements to try, and specifies a response, should an exception be thrown.

### Asynchronous catch

For example: Login

```javascript
tim.Login({
    email: "test email",
    password: "test"
  }).then(function(data) {
    console.log(data);
  })
  .catch(function(err) {
    console.log(err);
    console.log(err.message);
  })
```

For example: Get

```javascript
tim.X('user').Get()
  .then(function(data) {
    console.log(data);
  })
  .catch(function(err) {
    console.log(err);
    console.log(err.message);
  })
```

### Synchronous catch

For example: Login

```javascript
try {
  await tim.Login({
    email: "test email",
    password: "test"
  });
} catch (err) {
  console.log(err);
  console.log(err.message);
}
```

For example: Get

```javascript
try {
  await tim.X('user').Get();
} catch (err) {
  console.log(err);
  console.log(err.message);
}
```

{% hint style="info" %}
To Be Continued

This page is just an unfinished draft. The author is writing now. Welcome to donate, cheer for the author.
{% endhint %}