Develop Reference

Filter Multidimensional Array

I have my dataset configured as
var x = [
{"phaseName":"Initiation","phaseID":"595e382f1a1e9124d4e2600c"},
{"phaseName":"Execution","phaseID":"595e38321a1e9124d4e2600d"}
]
I want to write some function which give the output of filtered data.
For example
var y ="Initiation"
samplefunction(y)
and i get the whole line of {"phaseName":"Initiation","phaseID":"595e382f1a1e9124d4e2600c"}

Use Array#filter
var x = [{
"phaseName": "Initiation",
"phaseID": "595e382f1a1e9124d4e2600c"
},
{
"phaseName": "Execution",
"phaseID": "595e38321a1e9124d4e2600d"
}
];
function filter(phaseName) {
return x.filter(item => {
return item.phaseName === phaseName;
});
}
console.log(filter('Initiation'));

You can also use a simple for loop:
var x = [{
"phaseName": "Initiation",
"phaseID": "595e382f1a1e9124d4e2600c"
},
{
"phaseName": "Execution",
"phaseID": "595e38321a1e9124d4e2600d"
}
];
var y = "Initiation";
function samplefunction(value) {
var newArr = new Array(); //creating a new array to store the values
for (var i = 0; i < Object.keys(x).length; i++) { //looping through the original array
if (x[i].phaseName == value) {//check if the phase name coresponds with the argument
newArr.push(x[i]); //push the coressponding value to the new array
}
}
return newArr; //return the new array with filtered values
}
var result = samplefunction(y);
console.log(result);

You could test all properties for the wanted value and filter the array.
function filter(array, value) {
return array.filter(function (object) {
return Object.keys(object).some(function (key) {
return object[key] === value;
});
});
}
var data = [{ phaseName: "Initiation", phaseID: "595e382f1a1e9124d4e2600c" }, { phaseName: "Execution", phaseID: "595e38321a1e9124d4e2600d" }];
console.log(filter(data, "Initiation"));

JavaScript - find unique values in array of objects, with count and create a new array of objects

I have an array of objects as below:
var arr =[
{
price:20,
rule:a
},
{
price:10,
rule:b
},
{
price:5,
rule:a
},
{
price:50,
rule:b
},
{
price:70,
rule:b
}
]
I want to extract an array of objects out of this as below:
var filteredArr = [
{
rule:a,
countOfRule:2,
minPriceForThisRule:5
},
{
rule:b,
countOfRule:3,
minPriceForThisRule:10
}
]
This means:
1) I want to create new array with no. of objects as unique no. of rules in first array "arr"
2) Need to count the unique rule repetition and add as property in new array objects - given as "countOfRule"
3) Find the minimum price for in a category of unique rule - given as "minPriceForThisRule"
I have read similar answers on SO and was able to get first 2 conditions only, and that too were not in the format as i need.
What I tried, referring to links on SO:
var ff = {},e;
for (var i = 0,l=arr.length; i < l; i++) {
e = arr[i];
ff[e.rule] = (ff[e.rule] || 0) + 1;
}
But this gives only a single object as
{
a : 2,
b: 3
}

You can do this with forEach and thisArg optional parameter.
var arr = [{"price":20,"rule":"a"},{"price":10,"rule":"b"},{"price":5,"rule":"a"},{"price":50,"rule":"b"},{"price":70,"rule":"b"}],
r = [];
arr.forEach(function(e) {
if(!this[e.rule]) {
this[e.rule] = {rule: e.rule, countOfRule: 0, minPriceForThisRule: e.price}
r.push(this[e.rule]);
}
this[e.rule].countOfRule++;
if(this[e.rule].minPriceForThisRule > e.price) this[e.rule].minPriceForThisRule = e.price;
}, {});
console.log(r)

I would use reduce. Something like:
var reduced = arr.reduce(function(memo, obj){
var rule = memo[obj.rule];
rule.countOfRule++;
if(!rule.minPriceForThisRule){
rule.minPriceForThisRule = obj.price;
} else{
if(obj.price < rule.minPriceForThisRule){
rule.minPriceForThisRule = obj.price;
}
}
return memo;
}, map);
where the initial map looks like:
var map = {
1: {
rule: 1,
countOfRule: 0,
minPriceForThisRule: null
},
2: {
rule: 2,
countOfRule: 0,
minPriceForThisRule: null
}
}
Of course you could dynamically create the map if needed.
https://plnkr.co/edit/wLw3tEx2SMXmYE7yOEHg?p=preview

This is how i would do this job,
var arr =[
{
price:20,
rule:"a"
},
{
price:10,
rule:"b"
},
{
price:5,
rule:"a"
},
{
price:50,
rule:"b"
},
{
price:70,
rule:"b"
}
],
reduced = arr.reduce((p,c) => { var fo = p.find(f => f.rule == c.rule);
fo ? (fo.countOfRule++,
fo.minPriceForThisRule > c.price && (fo.minPriceForThisRule = c.price))
: p.push({rule:c.rule, countOfRule:1, minPriceForThisRule: c.price});
return p;
},[]);
console.log(reduced);
Arrows might not work at IE or Safari. If that would be a problem please replace them with their conventional counterparts.

merging two array of objects with custom compare function with javascript

I have two array of objects like:
var A = [{title:"name1",count:5},{title:"name2",count:1},{title:"name3",count:3}];
and:
var B = [{title:"name2",count:7},{title:"name3",count:2},{title:"name4",count:3},{title:"name5",count:8}];
I need to merge this two array in one array and sum the "count" values in returned array when the "title" properties is same:
the last answer must be:
[{title:"name1",count:5},{title:"name2",count:8},{title:"name3",count:5},{title:"name4",count:3},{title:"name5",count:8}]
how can i do this???

You can use Array#forEach and Array#some to achieve a result
var M = A.concat(B)
var C = [];
M.forEach(function(a) {
var index;
if (C.some(function(c, i) { index = i; return a.title == c.title; })) {
C[index].count += a.count;
} else {
C.push(a);
}
});
console.log(C); // as you expect

Solution with Array.concat and Array.map functions:
var merged = A.concat(B), titles = [], result = [];
merged.map(function(obj){
if (titles.indexOf(obj.title) === -1) {
titles.push(obj.title);
result.push(obj);
} else {
result[titles.indexOf(obj.title)]['count'] += obj['count'];
}
});
console.log(result); // will output the expected array of objects

It can be done like this https://jsfiddle.net/menm9xeo/
var noMatch;
var A = [{title:"name1",count:5},{title:"name2",count:1},{title:"name3",count:3}];
var B = [{title:"name2",count:7},{title:"name3",count:2},{title:"name4",count:3},{title:"name5",count:8}];
//for each A, loop through B's. If a match is found combine the Counts in A.
for(var i=0;i<A.length;i++){
for(var j=0;j<B.length;j++){
if(A[i].title == B[j].title){
A[i].count += B[j].count;
}
}
}
//find all B's that were not combined with A in the previous step, and push them into A.
for(var i=0;i<B.length;i++){
noMatch = true;
for(var j=0;j<A.length;j++){
if(B[i].title == A[j].title){
B[i].count += A[j].count;
noMatch = false;
}
}
if(noMatch){A.push(B[i]);}
}

Heres a simple 3 line answer (minus the A/B vars); utilizes the fact that objects must have unique keys
var A = [{title:"name1",count:5},{title:"name2",count:1},{title:"name3",count:3}];
var B = [{title:"name2",count:7},{title:"name3",count:2},{title:"name4",count:3},{title:"name5",count:8}];
var o = {};
A.concat(B).forEach(function(a){o[a.title] = o.hasOwnProperty(a.title)? o[a.title]+a.count: a.count});
var AB = Object.keys(o).map(function(j){ return {title:j,count:o[j]} });

This proposal is merging and counting with a temporary object and Array#forEach()
The forEach() method executes a provided function once per array element.
var arrayA = [{ title: "name1", count: 5 }, { title: "name2", count: 1 }, { title: "name3", count: 3 }],
arrayB = [{ title: "name2", count: 7 }, { title: "name3", count: 2 }, { title: "name4", count: 3 }, { title: "name5", count: 8 }],
result = function (array) {
var o = {}, r = [];
array.forEach(function (a) {
if (!(a.title in o)) {
o[a.title] = { title: a.title, count: 0 };
r.push(o[a.title]);
}
o[a.title].count += a.count;
});
return r;
}(arrayA.concat(arrayB));
document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

Using lodash ._concat function :
var result = _.concat(A, B);
Fiddle

JavaScript “map” function

Looking at the map method in JavaScript, what am I doing wrong here?
// Input: [ { name: "Kevin"}, { name: "Bob" } ]
// Output: [ { "Kevin" :0 }, { "Bob": 1 } ]
var map = function(arr, property) {
var i = 0;
var m = arr.prototype.map(makeKv);
// Input: { name: "Kevin" }
// Output: { "Kevin" = i } // GLOBAL
function makeKv(item) {
return {
item: i++
};
};
console.log("m : " + m);
};
JSFiddle
Please also help me get rid of the global, too.

There are a few issues here:
First,
var m = arr.prototype.map(makeKv);
You don't need prototype here. You only use that when you are using the constructor, like Array.prototype.map. Here, you just need to do arr.map.
Second,
function makeKv(item) {
return {item: i++};
};
You never declare i anywhere. How can you add one to something that doesn't exist. You need to have var i = 0; before this.
Finally, return {item: i++}; will make a key called literally "item". You need to declare the object first (var ret = {};), then use [item] to set the value.
Array.map's callback is passed the element in the array as the 1st parameter, so item will be an object. You need to do item[property] to get the value you want.
P.S. Don't do "m : " + m in your console.log, that will concat strings, thus converting m to a string. Use , instead: console.log("m : ", m);
So, all together, try:
var map = function(arr, property) {
var i = 0;
var m = arr.map(makeKv);
function makeKv(item) {
var ret = {};
ret[item[property]] = i++;
return ret;
};
console.log("m : ", m);
}
DEMO: http://jsfiddle.net/FgdSj/3/
EDIT: Array.map's callback is passed the index in the array as the 2nd parameter, so var i = 0; isn't needed here:
var map = function(arr, property) {
var m = arr.map(makeKv);
function makeKv(item, index) {
var ret = {};
ret[item[property]] = index;
return ret;
};
console.log("m : ", m);
}
DEMO: http://jsfiddle.net/FgdSj/5/

arr.prototype.map(makeKv);
should be
arr.map(makeKv);
Now you have another issue since it will return
[ { item : 0}, { item : 1} ]
If you change the mapped function to
function makeKv(item) {
var x = {}
x[item.name] = i++;
return x;
};
it would give you what you want.
JSFiddle

Just call .map directly
arr.map(makeKv)
I, for whatever reason (maybe map is overridden), you want to use the Array.prototype's method
[].map.call(arr, makeKv);
Here's, it's all fixed up for you to match your desired output
// input: [{name: "Kevin"}, {name: "Bob"}], "name"
var map = function(arr, property) {
var i = 0;
function makeKv(item) {
var obj = {};
obj[item[property] = i++;
return obj;
};
return arr.map(makeKv);
}
var result = map([{name: "Kevin"}, {name: "Bob"}], "name");
console.log(result);
// [{"Kevin" : 0}, {"Bob" : 1}];

var map = function(arr, property) {
var i = 0;
var m = Array.prototype.map(makeKv);
// input: {name: "Kevin"}
// output: "Kevin" = i // GLOBAL
function makeKv(item) {
return {item: i++};
};
console.log("m : " + m);
return m;
}
map();

Remove JSON entry by value [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Delete from array in javascript
I have the following JSON object:
[id:84,id:92,id:123,id:2353]
How would I go about removing the item which the value is "123" using javascript?
or if I formatted the json as
[84, 92, 123, 2353]
How would it be removed in this case?

Assume you have this:
var items = [{ id: 84 }, { id: 92 }, { id: 123 }, { id: 2353 }];
var filtered = items.filter(function(item) {
return item.id !== 123;
});
//filtered => [{ id: 84 }, { id: 92 }, { id: 2353 }]

Supposing you actually have an object from a json in the json variable
for (key in json) {
if (json.hasOwnProperty(key) && json[key] == 123) {
delete json[key];
}
}

Shorter alternative would be:
var newArr = [{id:84}, {id:92}, {id:123}, {id:2353}].filter(function(a) {
return a.id != 123;
});
If you have this:
var arr = [{id:84}, {id:92}, {id:123}, {id:2353}]
To remove the item with value 123, you can do:
for(var i = 0; i < arr.length; i++) {
if(arr[i].id == 123) {
arr.splice(i, 1);
break;
}
}

function removeClass(obj, cls) {
var classes = obj.className.split(' ');
for(i=0; i<classes.length; i++) {
if (classes[i] == cls) {
classes.splice(i, 1);
i--; // (*)
}
}
obj.className = classes.join(' ');
}
var obj = { className: 'open menu menu' }
removeClass(obj, 'menu')
alert(obj.className)

You can use splice function, like this:
var data = [{id:84}, {id:92}, {id:123}, {id:2353}];
function remove(){
for(var i = 0, max = data.length; i < max; i++) {
var a = data[i];
if(a.id === 123) {
data.splice(i, 1);
break;
}
}
}
remove();

Seems like you want to avoid a loop. Assuming it's available, you can use .filter:
[{id:84},{id:92},{id:123},{id:2353}]
.filter(function (elem) { return elem.id !== 123; });
This technically does do a loop, but at least you don't have to look at it.

Assuming your "json" is really an array, like [84, 92, 123, 2353]:
var myString = "[84, 92, 123, 2353]";
var myArray = JSON.parse(myString);
var index = myArray.indexOf(123); // whatever value you are looking for
myArray.splice(index, 1);
http://jsfiddle.net/7vkK6/

Assuming I'm understanding your question and comments correctly you can do something like this:
var old_array = [{id: 84},...];
var new_array = [];
for(var i = 0, len = old_array.length; i++) {
if (old_array[i].id != 123) new_array.push(old_array[i]);
}

What you have currently is not JSON so I'll give you some different options.
If you have an Array arr = [84,92,123,2353] then
arr = arr.filter(function (x) {return x !== 123;}); // all occurrences
// OR
arr.splice(arr.indexOf(123), 1); // first occurrence only
If you have an Object obj = {"84": a, "92": b, "123": c, "2353": d}, a to d some expressions, then
delete obj['123']; // obj now {"84": a, "92": b, "2353": d}

1) JSON is a string, not an array or an object.
var json = "[1,2,3]";
2) Valid JSON NEEDS to be valid JS
var myJSObj = { 1,2,3 }, // broken
myJSArr = [ name : 1, name2 : 2 ]; // broken
3) If you have a JS Array, you can remove an element by using [].splice
var arr = [ 1, 2, 3, 4 ],
i = 0, l = arr.length,
test = 4;
for (; i < l; i += 1) {
if (arr[i] === test) { arr.splice(i, 1); } // remove 1 starting at i
}
4) If you have an object with named keys, you can use delete
var obj = { val : 1 };
delete obj.val;