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"高阶函数是一个将一个或多个函数作为参数的函数" ——ClojureBridge
高阶函数可以帮助增强你的Javascript,使你的代码简单、简练、可读性强。
Array.prototype.filter()
filter()方法创建一个新数组，其包含是符合条件的元素
用法：
var words = ["spray", "limit", "elite", "exuberant", "destruction", "present"];
var longWords = words.filter(function ( word ) {
//return true 则将该word push到longWords数组里
//return false 则布会将改word push到longWords数组里
return word.length > 6;
});
// Filtered array longWords is ["exuberant", "destruction", "present"]
在ES6中，可以使用箭头函数
var words = ["spray", "limit", "elite", "exuberant", "destruction", "present"];
var longWords = words.filter( word => word.length > 6);
// Filtered array longWords is ["exuberant", "destruction", "present"]
Array.prototype.map()
map()方法创建一个新数组，其结果是该数组中的每个元素都调用一个提供的函数后返回的结果
用法：
var numbers = [1, 5, 10, 15];
var doubles = numbers.map(function(x) {
return x * 2;
});
// doubles is now [2, 10, 20, 30]
// numbers is still [1, 5, 10, 15]
var numbers = [1, 4, 9];
var roots = numbers.map(Math.sqrt);
// roots is now [1, 2, 3]
// numbers is still [1, 4, 9]
Array.prototype.reduce()
reduce()方法适用于累加
var total = [0, 1, 2, 3].reduce(function(sum, value) {
return sum + value;
}, 0);
// total is 6
var flattened = [[0, 1], [2, 3], [4, 5]].reduce(function(a, b)
{
//concat() 方法用于连接两个或多个数组
return a.concat(b);
}, []);
// flattened is [0, 1, 2, 3, 4, 5]
