語法
arr.some(callback[, thisArg])
實例
function isBiggerThan10(element, index, array) { return element > 10; } [2, 5, 8, 1, 4].some(isBiggerThan10); // false [12, 5, 8, 1, 4].some(isBiggerThan10); // true
檢查數組中是否存在一個值
var fruits = ['apple', 'banana', 'mango', 'guava']; function checkAvailability(arr, val) { return arr.some(function(arrVal) { return val === arrVal; }); } checkAvailability(fruits, 'kela'); //false checkAvailability(fruits, 'banana'); //true
將任何值轉換為佈爾值
var TRUTHY_VALUES = [true, 'true', 1]; function getBoolean(a) { 'use strict'; var value = a; if (typeof value === 'string') { value = value.toLowerCase().trim(); } return TRUTHY_VALUES.some(function(t) { return t === value; }); } getBoolean(false); // false getBoolean('false'); // false getBoolean(1); // true getBoolean('true'); // true
源碼
// Production steps of ECMA-262, Edition 5, 15.4.4.17 // Reference: https://es5.github.io/#x15.4.4.17 if (!Array.prototype.some) { Array.prototype.some = function(fun/*, thisArg*/) { 'use strict'; if (this == null) { throw new TypeError('Array.prototype.some called on null or undefined'); } if (typeof fun !== 'function') { throw new TypeError(); } var t = Object(this); var len = t.length >>> 0; var thisArg = arguments.length >= 2 ? arguments[1] : void 0; for (var i = 0; i < len; i++) { if (i in t && fun.call(thisArg, t[i], i, t)) { return true; } } return false; }; }
sort語法
arr.sort([compareFunction])
數字排序
var numbers = [4, 2, 5, 1, 3]; numbers.sort(function(a, b) { return a - b; }); console.log(numbers); // [1, 2, 3, 4, 5]
實例
var stringArray = ['Blue', 'Humpback', 'Beluga']; var numericStringArray = ['80', '9', '700']; var numberArray = [40, 1, 5, 200]; var mixedNumericArray = ['80', '9', '700', 40, 1, 5, 200]; function compareNumbers(a, b) { return a - b; } console.log('stringArray:', stringArray.join()); console.log('Sorted:', stringArray.sort()); console.log('numberArray:', numberArray.join()); console.log('Sorted without a compare function:', numberArray.sort()); console.log('Sorted with compareNumbers:', numberArray.sort(compareNumbers)); console.log('numericStringArray:', numericStringArray.join()); console.log('Sorted without a compare function:', numericStringArray.sort()); console.log('Sorted with compareNumbers:', numericStringArray.sort(compareNumbers)); console.log('mixedNumericArray:', mixedNumericArray.join()); console.log('Sorted without a compare function:', mixedNumericArray.sort()); console.log('Sorted with compareNumbers:', mixedNumericArray.sort(compareNumbers)); stringArray: Blue,Humpback,Beluga Sorted: Beluga,Blue,Humpback numberArray: 40,1,5,200 Sorted without a compare function: 1,200,40,5 Sorted with compareNumbers: 1,5,40,200 numericStringArray: 80,9,700 Sorted without a compare function: 700,80,9 Sorted with compareNumbers: 9,80,700 mixedNumericArray: 80,9,700,40,1,5,200 Sorted without a compare function: 1,200,40,5,700,80,9 Sorted with compareNumbers: 1,5,9,40,80,200,700
字母排序
var items = ['réservé', 'premier', 'cliché', 'communiqué', 'café', 'adieu']; items.sort(function (a, b) { return a.localeCompare(b); }); // items is ['adieu', 'café', 'cliché', 'communiqué', 'premier', 'réservé']
排序圖
// the array to be sorted var list = ['Delta', 'alpha', 'CHARLIE', 'bravo']; // temporary array holds objects with position and sort-value var mapped = list.map(function(el, i) { return { index: i, value: el.toLowerCase() }; }) // sorting the mapped array containing the reduced values mapped.sort(function(a, b) { return +(a.value > b.value) || +(a.value === b.value) - 1; }); // container for the resulting order var result = mapped.map(function(el){ return list[el.index]; });
splice語法
array.splice(start, deleteCount[, item1[, item2[, ...]]])
實例
var myFish = ['angel', 'clown', 'mandarin', 'surgeon']; // removes 0 elements from index 2, and inserts 'drum' var removed = myFish.splice(2, 0, 'drum'); // myFish is ['angel', 'clown', 'drum', 'mandarin', 'surgeon'] // removed is [], no elements removed // myFish is ['angel', 'clown', 'drum', 'mandarin', 'surgeon'] // removes 1 element from index 3 removed = myFish.splice(3, 1); // myFish is ['angel', 'clown', 'drum', 'surgeon'] // removed is ['mandarin'] // myFish is ['angel', 'clown', 'drum', 'surgeon'] // removes 1 element from index 2, and inserts 'trumpet' removed = myFish.splice(2, 1, 'trumpet'); // myFish is ['angel', 'clown', 'trumpet', 'surgeon'] // removed is ['drum'] // myFish is ['angel', 'clown', 'trumpet', 'surgeon'] // removes 2 elements from index 0, and inserts 'parrot', 'anemone' and 'blue' removed = myFish.splice(0, 2, 'parrot', 'anemone', 'blue'); // myFish is ['parrot', 'anemone', 'blue', 'trumpet', 'surgeon'] // removed is ['angel', 'clown'] // myFish is ['parrot', 'anemone', 'blue', 'trumpet', 'surgeon'] // removes 2 elements from index 2 removed = myFish.splice(myFish.length -3, 2); // myFish is ['parrot', 'anemone', 'surgeon'] // removed is ['blue', 'trumpet']