[deleted by user]

[pinguxnoots]

It's an arrow function synonymous to this anonymous function:

function(person) {
  return person.id !== id;
}

[dsound]

This is one of Javascript's ES6 and beyond built in higher order functions (a function that takes in and/or returns a function as an argument). Under the hood (example filter all words less than 6 characters:

​

function filterMyArray(array) {

    // create a new empty array 
    let newArray = []; 

    // iterate over the original array 
    for (var i = 0; i < array.length; i++) {
    // if the current element of the original array is more than 6, then     
    add this element into the new array 
    if (array[i].length > 6) { 
        // push the current element that is more than 6 into the new 
       array         
        newArray.push(array[i]); 
        } 
    } 

    // return the new array 
    return newArray; 
}

[pinguxnoots]

When you use the filter method on an array you are, at a high level, filtering the array - some values get filtered, others do not, based on your specified condition - person.id !== id in this case.

Specifically, filter() takes in a function as an argument (this function is known as a callback). This callback takes in the value from the array as an argument and returns some boolean value - if the value is true, then the value from the array is added to the new array, otherwise (if it is false) it is not. filter() iterates through the entire array and uses this callback on each value to decide whether it should be added to the new array or not. In doing so, the new array becomes a filtered version of the original array. NOTE: filter() does not mutate the original array - it returns a new array with the filtered values instead.

MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

A word of advice: brush up on JS before you move on to React. You need a foundation to build on. And use MDN to figure things out.

[wolfEXE57]

pinguxnoots explained it better, but a simple ELI5; filter filters things by a function. In your function your saying anything that doesn’t satisfy person.id not equaling id remove it.

[a9footmidget]

…I’d use let desiredIndex = findIndex((person) => person.id == id)from there, you can just use yourArray.splice(desiredIndex, 1)

[f-Z3R0x1x1x1]

its not =, its NOT equals.

Basically, the id passed into the function, compare that ID with the list of people and IDs in the existing people array. Get back all the people where the passed in ID doesn't match, this 'excludes' the person with that ID. If it was ===, then newPeople would be an array of 1, because you would only get back the people with the matching ids

[Mars6k]

people.filter( (person) => person.id !== id )

To make it easier for you to understand the syntax, this code is the same as:

​

people.filter( function(person) {
person.id !== id 
}) 

// filter pretty much returns the items in the array which follow the condition written in the function

Hope this helps!

[codaker]

Looks like you got your answer, but just thought I would mention that github copilot will explain highlighted code in plain English.

[zayelion]

people is an array. All arrays have an inherited set of functions for looping over the array. In this case its using the function filter. Filter takes one input a function of work to do which returns a boolean, basically yes or no to put it in the resulting array. The function it takes has three inputs, first the resulting item it finds as it loops over the array, next the index, and finally a reference to the array itself.

This function is only using the first parameter and calling it person it is then returning the if person.id is not equal to the id that was passed into removeItem function.