Unable to set the value of `this` when defining a string prototype

Having trouble assigning a new value to the this keyword within a string prototype definition.

function testfunction(thisValue) {
    thisValue = thisValue || this;
    thisValue = "new test";
    console.log(thisValue);
    this = thisValue; // this throws error
}

Object.defineProperty(String.prototype, 'testfunction', { value: testfunction, enumerable: true });

let s = "i am a test"
s.testfunction()

When it comes to the Array object, I am familiar with using this.push. However, I am unsure how to assign a new value to the String.

Answer №1

Adding methods to the String prototype is definitely feasible. Despite some criticism, I believe that with caution and a thorough understanding of the consequences, it can be a valuable tool in programming. Remember, I'm not here to dictate your choices.

However, it's important to note that making these added methods enumerable can lead to issues when modifying standard prototypes. Additionally, for primitive types like String, Number, and Boolean, the underlying values cannot be changed as they are immutable. When calling a method on a string primitive, a temporary wrapper object is created and then discarded. This means that while methods can perform operations on the string, the original value remains untouched.

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