Keeping only certain properties in a JavaScript object

Just re-initialise the object:

myObj = {
    p1:   myObj.p1,
    p2:   myObj.p2,
    p100: myObj.p100
};

Another way is to delete certain properties, which is less effective:

var prop = ['p1', 'p2', 'p100'];
for (var k in myObj) {
    if (prop.indexOf(k) < 0) {
        delete myObj[k];
    }
}

This was the first hit when googling 'js keep only certain keys' so might be worth an update.

The most 'elegant' solution might just be using underscore.js

_.pick(myObj, 'p1', 'p2', 'p100')

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