JavaScript - First step - Arrays
阿新 • • 發佈:2018-12-11
建立陣列
任何型別的物件,都可以放入陣列中。
var shopping = ['bread', 'milk', 'cheese', 'hummus', 'noodles'];
shopping;
// (5) ["bread", "milk", "cheese", "hummus", "noodles"]
var sequence = [1, 1, 2, 3, 5, 8, 13];
var random = ['tree', 795, [0, 1, 2]];
存取、變更,陣列元素
shopping[0]; // returns "bread" shopping[0] = 'tahini'; shopping; // shopping will now return [ "tahini", "milk", "cheese", "hummus", "noodles" ]
獲取陣列長度
sequence.length;
// should return 7
var sequence = [1, 1, 2, 3, 5, 8, 13];
for (var i = 0; i < sequence.length; i++) {
console.log(sequence[i]);
}
部分陣列方法
字串和陣列之間的轉換
var myData = 'Manchester,London,Liverpool,Birmingham,Leeds,Carlisle'; var myArray = myData.split(','); myArray; myArray.length; myArray[0]; // the first item in the array myArray[1]; // the second item in the array myArray[myArray.length-1]; // the last item in the array var myNewString = myArray.join(','); myNewString; var dogNames = ['Rocket','Flash','Bella','Slugger']; dogNames.toString(); //Rocket,Flash,Bella,Slugger
新增、移除,陣列元素
var myArray = ['Manchester', 'London', 'Liverpool', 'Birmingham', 'Leeds', 'Carlisle']; // 向陣列末尾新增元素 myArray.push('Cardiff'); myArray; myArray.push('Bradford', 'Brighton'); myArray; var newLength = myArray.push('Bristol'); myArray; newLength; // 移除陣列末尾的元素 myArray.pop(); var removedItem = myArray.pop(); myArray; removedItem; // 向陣列起首新增元素 myArray.unshift('Edinburgh'); myArray; // 移除陣列起首元素 var removedItem = myArray.shift(); myArray; removedItem;
let customName = document.getElementById('customname');
let randomize = document.querySelector('.randomize');
let story = document.querySelector('.story');
function randomValueFromArray(array) {
return array[Math.floor(Math.random() * array.length)];
}
let storyText = "It was 94 fahrenheit outside, so :insertx: went for a walk. When they got to :inserty:, they stared in horror for a few moments, then :insertz:. Bob saw the whole thing, but was not surprised — :insertx: weighs 300 pounds, and it was a hot day.";
let insertX = ["Willy the Goblin", "Big Daddy", "Father Christmas"];
let insertY = ["the soup kitchen", "Disneyland", "the White House"];
let insertZ = ["spontaneously combusted", "melted into a puddle on the sidewalk", "turned into a slug and crawled away"];
randomize.addEventListener("click", result);
function result() {
let newStory = storyText;
let xItem = randomValueFromArray(insertX);
let yItem = randomValueFromArray(insertY);
let zItem = randomValueFromArray(insertZ);
newStory = newStory.replace(":insertx:", xItem);
newStory = newStory.replace(":inserty:", yItem);
newStory = newStory.replace(":insertz:", zItem);
if (customName.value !== '') {
let name = customName.value;
newStory = newStory.replace("Bob", name);
}
if (document.getElementById("uk").checked) {
let weight = Math.round(300 * 0.0714286) + " stone";
let temperature = Math.round((94 - 32) * 5 / 9) + " centigrade";
newStory = newStory.replace("300 pounds", weight);
newStory = newStory.replace("94 fahrenheit", temperature);
}
story.textContent = newStory;
story.style.visibility = 'visible';
}