forEach/JavaScript

# Web Site Writing Basics

# javascript

# Each

Access to Array members with forEach in JavaScript is a simple and popular iterate method. Use the Array.prototype.forEach method (). Each forEach application will call callback function once for every member in the syntax array. JavaScriptarray.forEach (callback (currentValue, index, array), thisArg);

The function callback description parameter (Required) to be run for each member in the current member currentValue array that is processing the index (Optional) index (index) of the current member array (Optional) the array that is processing thisArg (Optional). The value to be used as this. When running the code sample callback, this is the sample accessing the member in the array and displaying it. JavaScriptconst fruits = ["Apple," "Banana," "Cherry," "Date"];

/ / 1.Just access the value of the member (current value)

console. log ("--- Just access the value ---");

Fruits. Each (function (fruit) {

console. log (fruit);

});

/ / Output:

/ / Apple

/ / Banana

/ / Cherry

/ / Date

/ / 2.Access both values and indexes (currentValue, index) - Arrow Function is recommended

Console.log ("\ n--- Access to values and indexes ---");

Fruits. Each (fruit, index) = > {

console.log ('Fruit at index ${index} is: ${fruit}');

});

/ / Output:

/ / Fruit at index 0 is: Apple

/ / Fruit at index 1 is: Banana

/ / Fruit at index 2 is: Cherry

/ / Fruit at index 3 is: Date

Break / Return: Each forEach is designed to always process every member. If you need a mechanism to stop loops first, you should use a loop for or other methods such as some or every instead of no return value: the forEach method will always restore undefined. Unlike the map or filter method that returns to a new array, change the original value: the callback function can change the original array. If you change the value of the current value, it will not change the value of the array, but if you modify the object located in the array (such as the array of objects). ) That change will affect the original array.