nodejs how can i use multidimensional array and push values in it? - arrays

Question

i am trying to create a new multidimensional array from the data i am getting from 3rd part API.
"output":[
{
"is_indb":false,
"name":"adam",
"tokens":29
},
{
"is_indb":true,
"name":"aaron",
"tokens":2,
},
{
"is_indb":false,
"name":"adam",
"tokens":3,
},
{
"is_indb":false,
"name":"axel",
"tokens":5,
},
{
"is_indb":false,
"name":"andy",
"tokens":5,
},
{
"is_indb":false,
"name":"bob",
"tokens":5,
},
{
"is_indb":false,
"name":"aldo",
"tokens":5,
},
{
"is_indb":false,
"name":"julia",
"tokens":5,
}
]
i would like to create a new array and fill it with data from response.
but i would like to do some pre checks like
take only those whose, is_indb = false
take only those whose, name starts with a
so the final array will be, all those whosse is_indb = true and name starts with a
var newaray = [[adam,29],[adam,3],[axel,5],[andy,5],[aldo,5]];
so far i have tried using _pluck and getting some weird outputs. i am able to get sible elements using _pluck but cant get multiple items.
i can think of logic like this
var newaray = [];
if( (_pluck(msg.output,'is_indb') == false && ((_pluck(msg.output,'name').substring(0, 1) == "a")){
newaray.push( [ _.pluck(msg.output, 'name') , _.pluck(msg.output, 'token')] );
}

Answer 1

Use filter and map:
var filteredOutput = output
.filter(function(elem) {
// The return statement should return true,
// if you want the element to pass into the new array.
return elem.is_indb === false && typeof elem.name === "string" && elem.name.indexOf('a') === 0;
})
.map(function(elem) {
return [elem.name, elem.tokens];
});
or with ES6:
let filteredOutput = output
.filter(elem => elem.is_indb === false && typeof elem.name === "string" && elem.name.indexOf('a') === 0)
.map(elem => [elem.name, elem.tokens])
with ES6 and using regex (inspired by Peter Grainger's answer, but also case insensitive):
let filteredOutput = output
.filter(elem => elem.is_indb === false && /^a/i.test(elem.name))
.map(elem => [elem.name, elem.tokens])
and by the way, what you posted is an array of objects, not a multidimensional array, which is an array of arrays.

Answer 2

You could use a filter then a map?
const output = [
{
"is_indb":false,
"name":"adam",
"tokens":29
},
{
"is_indb":true,
"name":"aaron",
"tokens":2,
},
{
"is_indb":false,
"name":"adam",
"tokens":3,
},
{
"is_indb":false,
"name":"axel",
"tokens":5,
},
{
"is_indb":false,
"name":"andy",
"tokens":5,
},
{
"is_indb":false,
"name":"bob",
"tokens":5,
},
{
"is_indb":false,
"name":"aldo",
"tokens":5,
},
{
"is_indb":false,
"name":"julia",
"tokens":5,
}
]
const transform = output.filter(value => /^a/.test(value.name) && !value.is_indb)
.map(value => [value.name, value.tokens])
console.log(transform)

Answer 3

You can use _.filter and get the output in this form
op = [{ obj1 } ,{obj2}];
but as you want to remove some keys also then you can use _.pick
var op = _.filter(ip , function(obj){
if(obj.is_indb == false && obj.name[0] == 'a'){
return true;
}
else{
return false;
}
})
//so now you have all the entries filtered out
var opAltered = _.pick(op,['name','tokens']);
//you will get this result
/*
opAltered = [
{
name : <something>,
tokens : <something>
},{
...
}
]
*/
or If you want array you can use this
opAltered = _.map(op,['name','tokens'];
I have used more code to make you understand properly you can reduce it once you understand Thanks.