JavaScript - First step - Arrays

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创建数组

任何类型的对象，都可以放入数组中。

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、变更，数组元素

shopping[0];
// returns "bread"shopping[0] = 'tahini';
shopping;
// shopping will now return [ "tahini", "milk", "cheese", "hummus", "noodles" ]

获取数组长度

sequence.length;
// should return 7var sequence = [1, 1, 2, 3, 5, 8, 13];
for (var i = 0; i < sequence.length; i++) {console.log(sequence[i]);
}

部分数组方法

字符串和数组之间的转换

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 arrayvar myNewString = myArray.join(',');
myNewString;var dogNames = ['Rocket','Flash','Bella','Slugger'];
dogNames.toString(); //Rocket,Flash,Bella,Slugger

添加、移除，数组元素

var myArray = ['Manchester', 'London', 'Liverpool', 'Birmingham', 'Leeds', 'Carlisle'];// 向数组末尾添加元素
myArray.push('Cardiff');
myArray;
myArray.push('Bradford', 'Brighton');
myArray;var newLength = myArray.push('Bristol');
myArray;
newLength;// 移除数组末尾的元素
myArray.pop();var removedItem = myArray.pop();
myArray;
removedItem;// 向数组起首添加元素
myArray.unshift('Edinburgh');
myArray;// 移除数组起首元素
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';
}

 

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