How can I get the "e" elements inside of "arr" to be replaced by change0?

The arr array will be an input by the user and I need to change it there is no way to predict which element will be "e".

var arr = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"];

var change0 = 2

var change1 = 1

document.write(arr);

How can I get the "e" elements inside of "arr" to be replaced by change0?

The arr array will be an input by the user and I need to change it there is no way to predict which element will be "e".

var arr = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"];

var change0 = 2

var change1 = 1

document.write(arr);

• javascript
• arrays

Share Improve this question Follow edited Apr 16, 2017 at 11:06 ibrahim mahrir 31.7k55 gold badges4949 silver badges7878 bronze badges asked Apr 16, 2017 at 10:58 Peter TothPeter Toth 80011 gold badge99 silver badges3636 bronze badges

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8 Answers 8

Sorted by: Reset to default 2

You could use map() method and this will return new updated array and save original.

var arr = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"];
var change0 = 2;

var result = arr.map(e => e == 'e' ? change0 : e);
console.log(result)

You can do this using join and split methods.

var replace="change0";
var arr = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"];
console.log(arr.join().split('e').join(replace).split(','));

Run a loop for getting index of element "e" and then repeat until there are more elements left:

var arr = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"];

while (arr.indexOf("e") > 0){
    var index = arr.indexOf("e");
    arr[index] = "change0";
}
document.write(arr);

You could use Array#indexOf and search for all elements and change then with the given value.

var array = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"],
    search = "e",
    change = 2,
    p = array.indexOf(search);
    
while (p !== -1) {
    array[p] = change;
    p = array.indexOf(search, p + 1);
}

console.log(array);

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You can use indexOf to determine the index of the element in an array. So basically, you can just go like this:

arr[arr.indexOf('e')] = change0;

It will not work if you have multiple element that have the values of 'e'. It will only change the first one so you have to put it through a loop. Or use map.

Using forEach:

var arr = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"];

var change = "changed";

arr.forEach(function(v, i) {
  if(v === "e")
    arr[i] = change;
});

console.log(arr);

1. Convert to string
2. Replace 'e'
3. Convert back to array

var arr = [ "a", "b", "c", "d", "e", "f", "g", "h", "e", "j", "e"];

console.log((((arr.toString()).replace(/e/g,"changed"))).split(','));

If you intend to handle more than one letter, it’s best to prepare encoder/decoder (a function or an array) in advance. Then your job bees as simple as:

output = input.map(val => encoder[val] || val);

The || val part is for values not handled by the encoder.

Working example

In this example, we use split("") to convert string to array and join("") to do the opposite.

PrepareCodec:
    var Latin    = "abcdefghijklmnoprstuvyzABCDEFGHIJKLMNOPRSTUVYZ";
    var Cyrillic = "абцдефгхийклмнопрстувызАБЦДЕФГХИЙКЛМНОПРСТУВЫЗ";
    var encoder = {}, decoder = {};
    for (let i in Latin)    encoder[Latin[i]] = Cyrillic[i];
    for (let i in Cyrillic) decoder[Cyrillic[i]] = Latin[i];

EncryptionTest:
    var src = prompt("Enter text to encrypt:", "Hello, world!");
    var enc = src.split("").map(val => encoder[val] || val).join("");
DecryptionTest:
    enc = prompt("Enter text to decrypt:", enc);
    var dec = enc.split("").map(val => decoder[val] || val).join("");
FinalResult:
    prompt("Decrypted text:", dec);