如果值为空，未定义或为空，如何从对象和/或数组中删除属性？

Question

So I have a fairly complex object like this:

var obj = {
    v1:"ok", 
    v2:[
        {av1:"foo",  av2:null}, // notice there's a null here
        {av1:"thing", av2:"stuff"}
    ], 
    v3: null, 
    v4:{
        ov1:"slim",
        ov2:"shady",
        ov3:null  // null
    }, 
    v5:[], // empty
    v6:{} // empty
}

I'd like to get this back:

var obj = {
    v1:"ok", 
    v2:[{av1:"foo"},{av1:"thing", av2:"stuff"}], 
    v4:{ov1:"slim",ov2:"shady"}
}

I'm trying to write a function that can delete anything that is null, undefined, or empty, but it's quickly becoming a spaghetti nightmare, and doesn't work.

I feel like there's a shorter more elegant way to do this, but this is my code so far:

function deleteNulls(o){
    for(let i in o){
        if(typeof o[i] == "Object"){
            o[i] = deleteNulls(o[i])
        }
        else if(typeof o[i] == "Array"){
            o[i] = deleteNulls(o[i])
        }
        if(o[i] == null || o[i] == "undefined" || o[i] == [] | o[i] == {})
            delete o[i]
        else {
            if(typeof o == "Object"){
                delete this.o[i]
                return o
            }
            else if (typeof o == "Array")
                return o.filter(k => o[k] != null)
        }
    }
    return o
}

var obj = deleteNulls(obj)

I'm not interested in how to fix errors in the code above. I could get this to work if I wanted to,

I'm wondering if there's an easier way.

Answer 1

I'd suggest using something like lodash. It's tested and peer-reviewed for speed and efficiency.

Something like:

var result = _.omitBy(my_object, _.isNil);

This would remove all null values, you'll need to change the second parameter to remove empty objects and arrays.

Answer 2

It helped me writing this solution to split the logic into a recursive clean function (simplifying existing object structures) and a shouldKeep function (which tells you whether a key can be removed entirely from an object structure based on its value).

Demo Snippet:

 var object = { v1: "ok", v2: [{ av1: "foo", av2: null }, // notice there's a null here { av1: "thing", av2: "stuff" } ], v3: null, v4: { ov1: "slim", ov2: "shady", ov3: null // null }, v5: [], // empty v6: {} // empty } function shouldKeep (o) { if (Array.isArray(o)) { return o.length } else if (typeof o === 'object') { return o && Object.keys(o).length } return o != null } function clean (o) { if (Array.isArray(o)) { o.forEach(clean) var a = o.filter(shouldKeep) o.length = a.length for (var i = 0; i < a.length; i++) { o[i] = a[i] } } else if (o && typeof o === 'object') { Object.keys(o).forEach(function (k) { clean(o[k]) if (!shouldKeep(o[k])) delete o[k] }) } return o } console.log(clean(object)) 

 .as-console-wrapper { min-height: 100vh; } 

Answer 3

Here is my take at it. Should be good enough for most situations.

  var object = { v1: "ok", v2: [{ av1: "foo", av2: null }, // notice there's a null here { av1: "thing", av2: "stuff" } ], v3: null, v4: { ov1: "slim", ov2: "shady", ov3: null // null }, v5: [], // empty v6: {} // empty } function isEmpty(v) { return v == undefined || v == null || (Array.isArray(v) && v.length === 0) || (typeof v === 'object' && Object.keys(v).length === 0) } function removeFalsyFromObject(v) { var keys = Object.keys(v); keys.forEach(function(k){ var val = v[k]; if (isEmpty(val)) { delete v[k]; } else if (Array.isArray(val)) { removeFalsyFromArray(val); } else if (typeof val === 'object') { removeFalsyFromObject(val); } }) } function removeFalsyFromArray(a) { for (var i=0; i<a.length; i++) { var v = a[i]; if (isEmpty(v)) { a.splice(i,1); i--; } else if (Array.isArray(v)) { removeFalsyFromArray(v); } else if (typeof v === 'object') { removeFalsyFromObject(v); } } } function clean(obj) { removeFalsyFromObject(obj); return obj; } console.log(clean(object));