JavaScript Array Iteration
- forEach():
- map():
- filter():
- find():
- every():
- some():
- reduce():
forEach():
Executes a provided function once for each array element.
Example
let arr = [1, 2, 3, 4, 5];
arr.forEach(function(element) {
console.log(element);
});
// Output: 1, 2, 3, 4, 5
map():
Creates a new array populated with the results of calling a provided function on every element in the calling array.
Example
let arr = [1, 2, 3, 4, 5];
let mappedArray = arr.map(function(element) {
return element * 2;
});
// mappedArray is [2, 4, 6, 8, 10]
filter():
You can use Math.min.apply to find the lowest number in an array:
Example
Creates a new array with all elements that pass the test implemented by the provided function.
find():
Returns the value of the first element in the array that satisfies the provided testing function.
Example
let arr = [1, 2, 3, 4, 5];
let foundElement = arr.find(function(element) {
return element > 2;
});
// foundElement is 3
every():
Tests whether all elements in the array pass the test implemented by the provided function.
Example
let arr = [1, 2, 3, 4, 5];
let allGreaterThanZero = arr.every(function(element) {
return element > 0;
});
// allGreaterThanZero is true
some():
Tests whether at least one element in the array passes the test implemented by the provided function.
Example
let arr = [1, 2, 3, 4, 5];
let hasEven = arr.some(function(element) {
return element % 2 === 0;
});
// hasEven is true
reduce():
Executes a reducer function on each member of the array, resulting in a single output value.