> For the complete documentation index, see [llms.txt](https://javascript-1.gitbook.io/design-pattern/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://javascript-1.gitbook.io/design-pattern/behavioural-design-pattern/template-method.md).

# Template Method

Defer the exact steps of an algorithm to a subclass.

* Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.
* The Template Method pattern provides an outline of a series of steps for an algorithm.
* Objects that implement these steps retain the original structure of the algorithm but have the option to redefine or adjust certain steps.
* This pattern is designed to offer extensibility to the client developer.
* Template Methods are frequently used in general purpose frameworks or libraries that will be used by other developer.

```javascript
EX:
var datastore = {
    process: function() {
        this.connect();
        this.select();
        this.disconnect();
        return true;
    }
};
 
function inherit(proto) {
    var F = function() { };
    F.prototype = proto;
    return new F();
}

function run() {
    var mySql = inherit(datastore); 
    // implement template steps 
    mySql.connect = function() {
        console.log("MySQL: connect step");
    }; 
    mySql.select = function() {
        console.log("MySQL: select step");
    }; 
    mySql.disconnect = function() {
        console.log("MySQL: disconnect step");
    }; 
    mySql.process();
}

run();
// MySQL: connect step
// MySQL: select step
// MySQL: disconnect step
```