How to Delete an item from an array with specific string matching

Question

I want to be able to match a specific string (full match not partial match) and then delete that specific item from the array if it matches.

I have some code but it doesn't seem to be deleting the item from the array. I do wish for it to change the original array and not create a new array so I am not using filter.

How can I go about accomplishing this?

Current Code:

let recentSearches = [
  { name: "Chicago, IL" },
  { name: "Orlando, FL" },
  { name: "Dallas, TX" }
];

let stringToRemove = "Dallas, TX";

recentSearches.some(recent => {
  if (recent.name === stringToRemove) {
    const index = recentSearches.indexOf(stringToRemove);

    if (index !== -1) { //Never goes into this if
      recentSearches.splice(index, 1);
      console.log(recentSearches);
    }
  }
});

console.log(recentSearches);

JS Fiddle: enter link description here

It's not an array of strings, it's an array of objects.

Barmar
– Barmar

2021-07-27 21:03:06 +00:00
Commented Jul 27, 2021 at 21:03 — Barmar
– Barmar, Commented Jul 27, 2021 at 21:03

edemaine · Accepted Answer · 2021-07-27 21:11:43Z

If you don't mind the output being a different array, use filter:

const filteredSearches = recentSearches.filter((recent) => recent.name !== stringToRemove);

If you need to modify the array in-place, you should visit the elements in reverse order (in case of multiple matches, which causes indices to shift) like so:

for (let i = recentSearches.length-1; i >= 0; i--) {
  if (recentSearches[i].name === stringToRemove) {
    recentSearches.splice(i, 1);
  }
}

The problem with your code is you use recentSearches.indexOf, but recentSearches isn't an array of strings, so nothing matches. You could modify your code as follows, but it won't work correctly in case of multiple mathces:

recentSearches.forEach((recent, index) => {
  if (recent.name === stringToRemove) {
    recentSearches.splice(index, 1);
  }
});

Alternatively, you could use findIndex (as suggested in other comments and answers) as follows:

let index;
while (0 <= (index = recentSearches.findIndex((recent) => recent.name === stringToRemove)) {
  recentSearches.splice(index, 1);
}

Barmar · Accepted Answer · 2021-07-27 21:10:17Z

2

indexOf() is for finding exact matches. Since your array contains objects, they'll never be equal to stringToRemove.

Use findIndex() to get the index of an array element using a function that an compare the name property.

There's also no need for using some().

let recentSearches = [{
    name: "Chicago, IL"
  },
  {
    name: "Orlando, FL"
  },
  {
    name: "Dallas, TX"
  }
];

let stringToRemove = "Dallas, TX";

const index = recentSearches.findIndex(({
  name
}) => name == stringToRemove);
if (index !== -1) { //Never goes into this if
  recentSearches.splice(index, 1);
}

console.log(recentSearches);

edited Jul 27, 2021 at 21:10

answered Jul 27, 2021 at 21:05

Barmar

789k57 gold badges555 silver badges669 bronze badges

Comments

Keith · Accepted Answer · 2021-07-27 21:35:10Z

1

Another version of the findIndex, instead of using while, you could use for, a slight advantage here is that the index is then locally scoped inside the the for, were with a while loop you have the extra scope of the index, you could close the the scope of a let by doing { let index; while() {..}} but the for loop avoids that without using {}.

let recentSearches = [
    {name: "Chicago, IL"},
    {name: "Orlando, FL"},
    {name: "Dallas, TX"}
];
  
let stringToRemove = "Dallas, TX";

for (let index; index = recentSearches.findIndex(
  search => search.name === stringToRemove), index > -1;) 
    recentSearches.splice(index, 1);

console.log(recentSearches);

answered Jul 27, 2021 at 21:35

Keith

24.4k2 gold badges32 silver badges48 bronze badges

Comments

Praveen Thirumurugan · Accepted Answer · 2021-07-27 21:40:21Z

1

The JSON search is done wrongly.

I have added the perfect code to complete your requirement. Find all instances and delete them with a while loop. This will ensure duplicate search terms are also removed if any.

let recentSearches = [
    {name: "Chicago, IL"},
    {name: "Orlando, FL"},
    {name: "Dallas, TX"}
];
  
let stringToRemove = "Dallas, TX";

while (recentSearches.findIndex(search => search.name === stringToRemove) > -1) {
    const index = recentSearches.findIndex(search => search.name === stringToRemove);
    recentSearches.splice(index, 1);
}

console.log(recentSearches);

edited Jul 27, 2021 at 21:40

answered Jul 27, 2021 at 21:17

Praveen Thirumurugan

1,0771 gold badge14 silver badges29 bronze badges

2 Comments

Praveen Thirumurugan Over a year ago

@PA-GW ensure to add a while block to make sure the code is corner-case covered.

Praveen Thirumurugan Over a year ago

Oh sorry, the author corrected it now. Initially, it was like let stringToRemove = "Dallax, TX";

user12615060 · Accepted Answer · 2021-07-27 21:11:16Z

0

You can use findindex. Store it in a variable. And use splice

answered Jul 27, 2021 at 21:11

user12615060

Comments

Salem loress · Accepted Answer · 2022-04-10 07:59:31Z

You can use this code:

Array.prototype._arraycopy =  function(src, srcPos, dest, destPos, length) {
  while ((--length) >= 0) {
    dest[destPos++] = src[srcPos++];
  }
};

Array.prototype._fastRemove = function(es, i) {
  let newSize;
  if ((newSize = this.length - 1) > i) 
    this._arraycopy(es, i + 1, es, i, newSize - i);
  es[this.length = newSize] = null;
  this.length = newSize;
}

Array.prototype.__removeAt = function(index) {
  // Objects.checkIndex(index, size);
    const es = this;

    const oldValue =es[index];
    this._fastRemove(es, index);
    return oldValue;
}

Array.prototype.__removeAtValue = function(o) {
  const es = this;
  const size = this.size;
  let i = 0;
  (function() {
    if (o == null) {
        for (; i < size; i++)
            if (es[i] == null)
                return true;
    } else {
        for (; i < size; i++)
            if (Object.is(o, es[i]))
                return true;
    }
    return false;
  })()
  this._fastRemove(es, i);
  return true;
}

Array.prototype.remove = function(index) {
  return this.__removeAt(index)

}

Array.prototype.removeObj = function(obj) {
  return this.__removeAtValue(obj);
}

const arr = [1, 3, 4, 5, 10];
console.log(arr);
const rem = arr.remove(1)
console.log({ arr, rem });

const objs = [{ id: 1, name: "Hello" }, { id: 2, name: "Arrow" }, { id: 3, name: "Star" }]
console.log(objs);
const deleted = objs.removeObj({ id: 2, name: "Arrow" });
console.log({ objs, deleted })

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