Is there a way to incorporate a method into a JavaScript object dynamically without encountering any unusual errors?

Question

Is there a way to incorporate a method into a JavaScript object dynamically without encountering any unusual errors?

I am dealing with an array of JavaScript objects that I need to modify. Here is an example of the initial setup:

let headers = [
  {
    text: 'something',
    value: 'something else'
  },
  {
    text: 'something1',
    value: 'something else1'
  },
  // etc..
]

My goal is to loop through this array and add a custom method to each object, as shown below (please note that "this" refers to Vue in this context):

this.headers.map(h => {
    h['filter'] = function (value) {
        if (!this.filterValue) {
            return true;
        }

        return value.toLowerCase().includes(this.filterValue.toLowerCase());
    }
});

Despite my efforts, the added function does not work after the loop completes. Upon further investigation, I noticed an error related to "arguments" and "caller". Here's a link to the detailed error message: https://i.sstatic.net/tbm0p.png

Can anyone provide insights on how to troubleshoot and fix this issue?

javascript vue.js javascript-objects es6-map

Answer 1

Answer №1

One important concept to grasp is the use of this, particularly in JavaScript. It's a common topic in interviews, so it's worth delving into. Execute the code snippet below to observe how this behaves:

function Sample(headers = [{
    text: 'something',
    value: 'something else'
  },
  {
    text: 'something1',
    value: 'something else1'
  },
  // etc..
], filterValue = 'else1') {
  this.filterValue = filterValue
  this.headers = headers.map(h => ({
    ...h,
    filter: () => {
      if (!this.filterValue) {
        return true;
      }

      return h.value.toLowerCase().includes(this.filterValue.toLowerCase());
    }
  }))
}

console.log(new Sample().headers.map(x => x.filter()))

Answer 2

One important concept to grasp is the use of this, particularly in JavaScript. It's a common topic in interviews, so it's worth delving into. Execute the code snippet below to observe how this behaves:

function Sample(headers = [{
    text: 'something',
    value: 'something else'
  },
  {
    text: 'something1',
    value: 'something else1'
  },
  // etc..
], filterValue = 'else1') {
  this.filterValue = filterValue
  this.headers = headers.map(h => ({
    ...h,
    filter: () => {
      if (!this.filterValue) {
        return true;
      }

      return h.value.toLowerCase().includes(this.filterValue.toLowerCase());
    }
  }))
}

console.log(new Sample().headers.map(x => x.filter()))

Is there a way to incorporate a method into a JavaScript object dynamically without encountering any unusual errors?

Answer №1

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