JS getter

basic

Encountered with the following function as below:

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static get userFilter() {
    return {
        dataset1: {
            value: '...'
        },
        dataset2: {
            value: '...'
        }
    };
}

so question comes up: Whats the meaning of ‘static get’ in Javascript (ES6)?

According to the above answer,

  • static defines that this function inside class is static, which means you cannot call the func via the instance of the class

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    // e.g.
    class Agent {
        static get CIRCLE() {
          return 1;
        }
        static get SQUARE() {
          return 2;
        }
    }
    // you call this as a property directly
    Agent.CIRCLE; // 1
    // but call by an instance is not allowed
    const newAgent = new Agent();
    console.log(newAgent.CIRCLE); // undefined or TypeError: foo.classMethod is not a function

    Lookup: Static method | Class的基本语法 2.静态方法

  • get syntax binds an object property to a function that will be called when is property is looked up

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    // e.g.
    const obj = {
      log: ['example','test'],
      get latest() {
        if (this.log.length === 0) return undefined;
        return this.log[this.log.length - 1];
      }
    }
    console.log(obj.latest); // "test".

    Note: the above code will create a pseudo-property latest for object obj, which will return the last array item in log, but the attempt to assign a value to latest will not change it.
    For more details, see MDN>JavaScript reference>Functions>getter