diff --git a/docs/posts/javascript-references.md b/docs/posts/javascript-references.md index f6275c2..7ae8f11 100644 --- a/docs/posts/javascript-references.md +++ b/docs/posts/javascript-references.md @@ -544,7 +544,7 @@ Loops need *braking points* and can be used with Conditional (if...else/switch.. The `for` syntax is composed by 3 instructions `for (initialValue; conditional; incremental/decremental){command}`: ```javascript -for (let i = 1); i <= 10; i = i + 1){command} +for (let i = 1; i <= 10; i = i + 1){command} || || || \/ \/ \/ {INITIAL VALUE}{CONDITIONAL}{INCREMENTAL} @@ -728,16 +728,87 @@ arr[0] = "NewValue" ### Array methods -{explicar eles e trazer exemplos} - * `arr.push()` adds one, or more, elements to the end of the array and returns the new array lenght. -* `arr.unshift()` adds one, or more, elements to the beginning of the array and returns the new array lenght. + +```javascript +const arr = ["string1", "string2", 12, 15, "string3"] +arr.push("one or", "more", "elements") +``` + * `arr.pop()` removes the last element of the array. + +```javascript +const arr = ["string1", "string2", 12, 15, "pop this one"] +arr.pop() +``` + * `arr.shift()` removes the first element of the array. -* `arr.splice()` used to replace elements. + +```javascript +const arr = ["shift this one", "string2", 12, 15, "pop this one"] +arr.shift() +``` + +* `arr.unshift()` adds one, or more, elements to the beginning of the array and returns the new array lenght. + +```javascript +const arr = ["string1", "string2", 12, 15, "string3"] +arr.unshift("zero", "unshift", "test") +``` + +* `arr.splice()` used to remove and replace elements. + +```javascript +const arr = ["string0", "string1", 2, 3, "remove 4", "remove 5"] +arr.splice(4, 2) //Start position, number of elements to delete + + +const arr = ["string0", "string1", 2, 3, "number this 4", "number this 5"] +arr.splice(4, 2, "quatro", "cinco") //Start position, number os elements to replace, replace value, replace value. +``` + * `arr.slice()` select elements of an array in a new array. -* `arr.map()` used for repetition loops. Run commands in each array element and creates a new array with the results. -* `arr.forEach()` used for repetition loops. Run commands in each array element and saves results in the same array. + +```javascript +const arr = ["string0", "string1", 2, 3, "quatro", "cinco", 6, 7, 8, 9, 10] +arr.slice() //Copy the array +arr.slice(2, 6) // Select elements from index 2 to 6 +``` + +* `arr.map()` expects a function as its argument. This function is then called for each element in the array. + +```javascript +const arr = [0, 1, 2, 3, 4, 5] +const mappedArr = arr.map(plus) + +function plus(value, index, arr) {return value + 1} +console.log(mappedArr) +``` + +* `arr.forEach()` used for repetition loops. Run commands in each element of the array and saves results in the same array. + +```javascript +const arr = [0, 1, 2, 3, 4, 5] +arr.forEach(plusFunction) + +function plusFunction(item, index, array) { + console.log(item + 1); +} + +//with arrow function +arr.forEach(item => {console.log(item + 1);}) +``` + +#### Locating content inside a array + +The methods `indexOf()`, `lastIndexOf()`, and `includes()` are used to locate content inside arrays. + +```javascript +const arr = [0, 1, 2, 3, 4, 5] +arr.indexOf(3) // Returns the index of the first occurrence of 3 +arr.lastIndexOf(3) // Returns the index of the last occurrence of 3 +arr.includes(3) // Returns true if the array contains 3 +``` ### Array properties