how to map an array of items to a new array in lowercase Javascript

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Trying to map the animal_names to a new array and lowercase them.

const zooAnimals = [
  { animal_name: "Jackal, asiatic", population: 5, scientific_name: "Canis aureus", state: "Kentucky" },
  { animal_name: "Screamer, southern", population: 1, scientific_name: "Chauna torquata", state: "Alabama" },
  { animal_name: "White spoonbill", population: 8, scientific_name: "Platalea leucordia", state: "Georgia" },
];

const lowCaseAnimalNames = [];

zooAnimals.map(function(arrItem){
  lowCaseAnimalNames = arrItem.animal_name.toLowerCase
});

console.log(lowCaseAnimalNames);

toLowerCase() is a method, to call or invoke that you have to specify () after the method name.

Also since map() creates a new array populated with the results of calling a provided function on every element in the calling array, you can simply return the modified item.

const zooAnimals = [
  { animal_name: "Jackal, asiatic", population: 5, scientific_name: "Canis aureus", state: "Kentucky" },
  { animal_name: "Screamer, southern", population: 1, scientific_name: "Chauna torquata", state: "Alabama" },
  { animal_name: "White spoonbill", population: 8, scientific_name: "Platalea leucordia", state: "Georgia" },
];

const lowCaseAnimalNames = zooAnimals.map(function(arrItem){
  return arrItem.animal_name.toLowerCase();
});

console.log(lowCaseAnimalNames);

Return all values from array in lowercase using for loop instead of map, In JavaScript, you can use the Array.map() method to iterate over all elements and then use the string methods to change the case of the� Definition and Usage The map () method creates a new array with the results of calling a function for every array element. The map () method calls the provided function once for each element in an array, in order. Note: map () does not execute the function for array elements without values.

.map() will build a new Array with the returned value, so you should assign it directly to lowCaseAnimalNames

.toLowerCase() is a function, so needs () to invoke it

With your original map, you would also have issue with lowCaseAnimalNames = arrItem.animal_name.toLowerCase() - As this would be trying to overwrite a const variable which isn't allowed

const zooAnimals = [
  { animal_name: "Jackal, asiatic", population: 5, scientific_name: "Canis aureus", state: "Kentucky" },
  { animal_name: "Screamer, southern", population: 1, scientific_name: "Chauna torquata", state: "Alabama" },
  { animal_name: "White spoonbill", population: 8, scientific_name: "Platalea leucordia", state: "Georgia" },
];

const lowCaseAnimalNames = zooAnimals.map(function(arrItem) {
  return arrItem.animal_name.toLowerCase();
});

console.log(lowCaseAnimalNames);

How to lowercase or uppercase all array values in JavaScript, What if I wanted to make all the items in array to uppercase letters. applies a function to them and pushes the results into a new array: function toUpper(item) { return item.toUpperCase(); } var stockUppercase = inStock.map(toUpper); Since version 6 of JavaScript, there is also a shorthand notation for� You can use $.map() in order to apply String.toUpperCase() (or String.toLocaleUpperCase(), if appropriate) to your array items: var upperCasedArray = $.map(array, String.toUpperCase); Note that $.map() builds a new array.

array.map() method will create a new array of elements based on the given function and return the new array for you.

  const zooAnimals = [
        { animal_name: "Jackal, asiatic", population: 5, scientific_name: "Canis aureus", state: "Kentucky" },
        { animal_name: "Screamer, southern", population: 1, scientific_name: "Chauna torquata", state: "Alabama" },
        { animal_name: "White spoonbill", population: 8, scientific_name: "Platalea leucordia", state: "Georgia" },
      ];

    let lowCaseAnimalNames = zooAnimals.map((arrItem) => arrItem.animal_name.toLowerCase());
    console.log(lowCaseAnimalNames);

All items in an array to uppercase?, Trying to map the animal_names to a new array and lowercase them. const zooAnimals = [ { animal_name: "Jackal, asiatic", population: 5,� toString () converts an array to a string separated by a comma. join () combines all array elements into a string. concat combines two arrays together or add more items to an array and then return a new array. push () adds item (s) to the end of an array and changes the original array.

how to map an array of items to a new array in lowercase Javascript, Syntax. str .toLowerCase(). Return value. A new string representing the calling string converted to lower case. Description. It basically loops through all elements of an array, applies a function to them and pushes the results into a new array: function toUpper ( item ) { return item . toUpperCase (); } var stockUppercase = inStock . map ( toUpper );

String.prototype.toLowerCase(), Return an array with the square root of all the values in the original array: The map() method creates a new array with the results of calling a function for every� Use Case The use case is to convert an array of objects into a hash map based on string or function provided to evaluate and use as the key in the hash map and value as an object itself.

JavaScript Array map() Method, Back when I began my new career as a web developer, the fact that I could loop And here is Array.map() creating a new array of objects: (which first converts all the characters to uppercase, lowercase would work too,� If callback needs to be working with the actual values of the array, specify the first parameter of callback as a reference. Then, any changes made to those elements will be made in the original array itself. Or directly via foreach loop using references: foreach($yourArray as &$value) $value = strtolower($value);

Comments
  • .toLowerCase() - It's a function, you need () to invoke it
  • Use return arrItem.animal_name.toLowerCase(); and set lowCaseAnimalNames equal to the return of running .map() instead of an empty array