reduce()Method receives a function as an accumulator (accumulator), and each value (from left to right) in the array begins to merge and eventually a value.concept: invokes the specified callback function for all elements in the array. The return
This article mainly introduces the summary, syntax, parameters, and working principle of the reduce JavaScript array method, which is easy to understand. You can check Array. prototype. reduce ()
Overview
The reduce () method is an instance method
Many times you need to accumulate an array of items to get a value (for example, sum). If you come across a similar problem, what do you think of the method? Would it be like me to think about using for or while looping, iterating over arrays,
basic functions of array manipulationThe key name and value of the arrayArray_values ($arr); Gets the value of the array Array_keys ($arr), gets the key name of the array array_flip ($arr), and the values in the array are exchanged with the key
Basic functions of array manipulationThe key name and value of the arrayArray_values ($arr); Get the value of an arrayArray_keys ($arr); Gets the key name of the arrayArray_flip ($arr); the values in the array are exchanged with the key names (if
Tag: false equals SAR dev Red initialize ice parsing newTalk about array traversal methodsThere are several ways to iterate the JS array:
Every
Some
Filter
Foreach
Map
Reduce
Next, we will exchange each other.Every (
Basic concepts: The reduce () method receives a function as an accumulator, and each value (from left to right) in the array begins to shrink, resulting in a value.Reduce each element in the array to execute a callback function in turn. Does not
Shuffle describes the process of data from the map task output to the reduce task input.Personal Understanding:The results of map execution are saved as a local file:As long as map execution is complete, the in-memory map data will be saved to the
Here are some snippets of code about the JavaScript array method that the individual collects and summarizes in the work, and reduce subsequent encounters with other scenarios that use this function will be added in succession, as a memo.JavaScript
The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion;
products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the
content of the page makes you feel confusing, please write us an email, we will handle the problem
within 5 days after receiving your email.
If you find any instances of plagiarism from the community, please send an email to:
info-contact@alibabacloud.com
and provide relevant evidence. A staff member will contact you within 5 working days.