1 let log = console.log.bind(console); 2 let person = [ 3 {id: 0, name: "小明"}, 4 {id: 1, name: "小张"}, 5 {id: 2, name: "小李"}, 6 {id: 3, name: "小孙"}, 7 {id: 1, name: "小周"}, 8 {id: 2, name: "小陈"}, 9 ]; 10 11 let obj = {}; 12 13 person = person.reduce((cur,next) => { 14 obj[next.id] ? "" : obj[next.id] = true &&cur.push (Next); 15 return cur; 16 }, []) // Set default type array cur, and the initial value is an empty array . 17 log (Person);
After printing person, we can get an array of de-duplicated.
Of course, redecu () in addition to and accumulated weights, there are many features, such as multi-dimensional arrays may be flat -
var flattened = [[0, 1], [2, 3], [4, 5]].reduce(function(a, b) {
return a.concat(b);
}, []); // [0,1,2,3,4,5]
In fact, for an array of objects, the traditional method to do anything heavy, as forEach (), filter () and other iterative method not so that; really do go heavy elegance, is a new method ES5 increase --reduce ( )
reduce () method takes a callback function as the first argument, and the callback function accepts four parameters, namely:
1.previousValue => initial value or a correction value is superimposed on the function;
2. currentValue => The callback (cycle) the value to be executed;
3. index => "currentValue" index value;
4. arr => array itself;
reduce () method returns the last call to the callback function's return value;
And then tell the outside question, referred to the weight, many people will think ES6 the Set; but according to my experiments, Set or go for the basic types of heavy, if Set each item is an object, it is not going to heavy, j if any object is exactly the same -
the let ARR = new new the Set ([
{ID: 0, name: "Bob"},
{ID: 0, name: "Bob"},
{ID: 0, name: "Bob"},
{ID: 0, name: "Bob"}
]);
the console.log ([... ARR]); // this is still an object 4