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JavaScript Design Patterns for Coding Interviews

Challenge: Solution Review

Explore the singleton pattern implementation that controls object creation in JavaScript. Understand how to restrict instantiation to a single instance while managing default and custom values effectively. This lesson helps you grasp design patterns critical for optimizing object construction in coding interviews.

We'll cover the following...

Solution #

Node.js
let configure = null;
class ConfigureVals{
    constructor(initvalues){
        this.xpoint = initvalues.xpoint || 0;
        this.ypoint = initvalues.ypoint || 0;
        this.shape = initvalues.shape || null;
    }
    static getConfiguration(initvalues){
        if (!configure) {
            configure = new ConfigureVals(initvalues)
            }
            return configure;
    }
}
var configureObj1 = ConfigureVals.getConfiguration({ "xpoint": 8, "ypoint" : 9, "shape" : "rectangle" });
console.log(configureObj1);
var configureObj2 = ConfigureVals.getConfiguration({ "xpoint": 2, "ypoint": 4, "shape" : "circle" });
console.log(configureObj2);

Explanation

In the solution, the first line defines the variable configure which stores the reference to the first instance of ConfigureVals. This variable is only initialized once.

The constructor of the class accepts the object parameter initvalues. It defines and initializes the values xpoint, ...