Object
object sort by value
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| const obj = {
'us': {'population': 331449281},
'jp': {'population': 125360000},
'in': {'population': 1352642280}
}
Object.keys(obj).sort((a, b) => obj[a]['population'] - obj[b]['population']).map(item => obj[item])
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注意
用数字作为对象的key，内部会自动转换为string
Array
concat
concat(value0, value1, ... , valueN)
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| const array1 = ['a', 'b', 'c'];
const array2 = ['d', 'e', 'f'];
const array3 = array1.concat(array2);
console.log(array3);
// expected output: Array ["a", "b", "c", "d", "e", "f"]
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map
map(function callbackFn(element, index, array) { ... }, thisArg)
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| const array1 = [1, 4, 9, 16];
// pass a function to map
const map1 = array1.map(x => x * 2);
console.log(map1);
// expected output: Array [2, 8, 18, 32]
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filter
filter(function callbackFn(element, index, array) { ... }, thisArg)
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| const words = ['spray', 'limit', 'elite', 'exuberant', 'destruction', 'present'];
const result = words.filter(word => word.length > 6);
console.log(result);
// expected output: Array ["exuberant", "destruction", "present"]
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参考
Standard built-in objects Array
Array.prototype.concat()
Array.prototype.map()
Array.prototype.filter()