过滤Javascript对象数组

Question

I am trying to get a new array object based on two of them.

log1 = {1:"London",2:"New york",4:"Berlin"};
log2 = [{id:1, location:"EU"},{id:2, location:"US"},{id:18, location:"Asia"}];

I want to make sure that log1 keys all exist in log2 and, if not, I want to delete it. So for this will be:

 result = {1:"London",2:"New york"};

I couldn't do it with filter as it take only one object. Is there any way to filter based on two object arrays? Is there any neat way to do it ?

Answer 1

Here is how you can do it in pure js:

    log1 = {1:"London",2:"New york",4:"Berlin"};
    log2 = [{id:1, location:"EU"},{id:2, location:"US"},{id:18, location:"Asia"}];

    for (var prop1 in log1) {
        var found = false;
        for (var i = 0; i < log2.length; i++) {
            if (log2[i].id.toString() === prop1) {
                found = true;
                break;
            }
        }
        if (!found) {
            delete log1[prop1]
        }
    }

Answer 2

If you are using a recent version of JS with Array.map() , Array.filter() and Object.keys() you could try the following for a slightly more functional approach:

var log1 = {
    1: "London",
    2: "New york",
    4: "Berlin"
};

var log2 = [
    {id: 1,  location: "EU"},
    {id: 2,  location: "US"},
    {id: 18, location: "Asia"}
];


var ids = log2.map(function(obj) { return obj.id; }).map(String);

Object.keys(log1).filter(function(key) {
    return ids.indexOf(key) === -1;
}).forEach(function(k) {
    delete log1[k];
});

console.log(log1);

Should yield:

{ '1': 'London', '2': 'New york' }

Example: http://repl.it/RnF/2

Hope this helps :)

Edit

Otherwise, for browser compatibility and much more you could consider lodash or underscore as suggested by other posters. Or use a polyfill!

MDN provides polyfills at the bottom of each of the following pages for older environments (in case you require the compatibility):

• Object.keys()
• Array.map()
• Array.filter()

Answer 3

Use http://underscorejs.org/

It has pluck,filter and map functions that can help you out.. Its quite powerful..