Summarize the usage of Array method in js

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Some methods of JS Array are very commonly used in practice. They are compiled and recorded here, firstly for frequent review, and secondly for everyone’s convenience

Map

map(): Returns a new Array, each element is the result of calling function

Syntax: array.map(function(currentValue,index,arr), thisValue)

Example:

var numbers = [65, 44, 12, 4], changedValue;
function multiplyArrayElement(num) {
    return num * 2;
}
(function myFunction() {
    changedValue = numbers.map(multiplyArrayElement);
})()
console.log(changedValue);

Filter

##filter(): Returns an array of elements that meet function conditions

Syntax: array .filter(function(currentValue,index,arr), thisValue)

Example:

var ages = [32, 33, 16, 40], changedValue;    
function checkAdult(age) {
    return age >= 18;
}
(function myFunction() {
    changedValue = ages.filter(checkAdult);
})()
console.log(changedValue);

Somesome(): Returns a boolean, Determine whether any element meets the function condition

Syntax: array.some(function(currentValue,index,arr),thisValue)

Example:

var ages = [3, 10, 18, 20], changedValue;
function checkAdult(age) {
    return age >= 18;
}
(function myFunction() {
   changedValue = ages.some(checkAdult);
})()
console.log(changedValue);

Every every(): Returns a boolean to determine whether each element meets the function condition

Syntax: array.every(function(currentValue,index,arr), thisValue)

Example:

var ages = [32, 33, 16, 40], changedValue;
function checkAdult(age) {
    return age >= 18;
}
(function myFunction() {
    changedValue = ages.every(checkAdult);
})()
console.log(changedValue);

ForEachforEach(): No return value, just call function for each element

Syntax: array.forEach(function(currentValue , index, arr), thisValue)

Example:

var numbers = [4, 9, 16, 25],changedValue;
function myFunction(item, index, arr) {
  arr[index] = item + 1;  
}
numbers.forEach(myFunction);
console.log(numbers);

Related recommendations:

Summary of Array object method attributes in javacsript

Summary of array and string methods in javascript_Basic knowledge

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