Related
I have array of objets like:
var MyArray = [] ,
Person = {},
[
{
name: 'John',
surname: 'Smith',
age: '22'
},
{
name: 'Jesica',
surname: 'Garou',
age: '31'
},
{
name: 'Max',
surname: 'Jolie',
age: '50'
}
]
I want to check , if my data has name 'John' that don't add new person , if not , then add new person with name 'John' and etc.
Thanks in advance .
You could deal with it using Array#find. I assume that you want to mutate your original array.
let arr = [{
name: 'Jesica',
surname: 'Garou',
age: '31'
},
{
name: 'Max',
surname: 'Jolie',
age: '50'
}
];
const obj = {
name: 'John',
surname: 'Smith',
age: '22'
};
const ensure = ({ name, ...z }) => {
if (!arr.find(v => v.name === name)) {
arr.push({ name, ...z });
}
}
ensure(obj);
console.log(arr);
You can use map but you have to know that map iterates through all elements in the array, whereas findIndex returns the first element index that equals the condition and stops the loop.
var MyArray = [
{
name: 'John',
surname: 'Smith',
age: '22'
},
{
name: 'Jesica',
surname: 'Garou',
age: '31'
},
{
name: 'Max',
surname: 'Jolie',
age: '50'
}
];
if(MyArray.findIndex(index => index.name === "John") > -1)
console.log("Found!");
else
console.log("Not found!");
To check if a name already exists in an array, you can make use of array.some function. It will check if name provided already exits or not.
If not then you can write the code to push the object in the array.
I have used the sample names John and Anne. For John, the function isAlreadyPresent returns true. For Anne, it returns false.
let arr = [
{
name: 'John',
surname: 'Smith',
age: '22'
},
{
name: 'Jesica',
surname: 'Garou',
age: '31'
},
{
name: 'Max',
surname: 'Jolie',
age: '50'
}
];
function isAlreadyPresent(name) {
return arr.some(a => a.name === name );
}
console.log('John already exists?',isAlreadyPresent('John'));
console.log('Anne already exists?',isAlreadyPresent('Anne'));
Maybe a name Map could be useful:
var byNam e =new Map(myArray.map(el=>[el.name,el]));
So you can easily do:
if (byName.has("John")){
alert("already exists");
} else {
var obj = { name: "John" };
Map.set(obj.name,obj);
myArray.push(obj);
}
The upper can be achieved with a Set also, but you may also want to do this:
byName.get("John").age=15;
You'll need to loop through all of the objects and check each of their name values. At worst runs in O(n) time.
For example, to check if "John" is a name in the array:
var inArray = false; // Have we found the name in the array yet?
for (var i = 0; i < MyArray.length; i++) { // Loop through the array of objects
if (MyArray[i].name=="John") { // If the name field is equal to "John"
inArray = true; // Name is in the array
break; // Exit the loop
}
}
var searchTerm = "John",
index = -1;
for(var i = 0, len = MyArray.length; i < len; i++) {
if (MyArray[i].name === searchTerm) {
alert("matched string");
index = i;
break;
}
}
You can make a search function like this that:
const index = (array, name) => {
// Search for the string "name" in your array
for (let i in array){
// Look at every element in the array, if an element has the
// corresponding name, return its index
if (array[i].name === name) return i;
}
return -1;
// If you found nothing, return -1
}
let position = index(myArray, "John");
Traditionally we use a constructor to build many similar objects. However, how that is OOP and is out of the scope of what you are asking.
Here we can use a for... in loop to iterate though MyArray, and check that each object does not include the name John.
function addJohn () {
for (let iterator in MyArray) { // You can also use for... of, but it will break in Node.
if (MyArray[iterator].name == "John") {return}; //You can also replace the string with a variable name to check that all objects do not have the variable in them.
else continue;
}
// you can now put in your new object here.
}
I want to deep merge 2 javascript objects with similar properties in a reducer. The catch is the two objects have arrays as their properties and I need them to be concatenated instead of replaced. Basically something like this:
var x = {
name: 'abc',
family: {
children: [
{name: 'xxx'},
{name: 'zzz'}
]
}
};
var y = {
name: 'abc',
family: {
children: [
{name: 'yyy'}
]
}
};
will result on
var y = {
name: 'abc',
family: {
children: [
{name: 'xxx'}, {name: 'zzz'}, {name: 'yyy'}
]
}
};
any suggestion? I prefer lodash based solution if possible. Also, since it's in reducer, I cannot just replace the property with new object
objects have arrays as their properties and I need them to be
concatenated instead of replaced
For your simple example it would be enough to use Array.prototype.concat() function:
var x = {name: 'abc', family:{children:[{name: 'xxx'}, {name: 'zzz'} ] }}, y = {name: 'abc', family: {children: [{name: 'yyy'}]}};
y.family.children = y.family.children.concat(x.family.children);
console.log(y);
If you're already using lodash, check if mergeWith doesn't do what you want... (see this so answer for example).
Anyway here is a quick function that should do what you want. Be warned that it does very little in terms of checking, and only merges properties that are in the first object (since you said that your objects are similar).
Also it doesn't mutate the objects but instead creates a new one.
function merge(a, b){
var ret = {};
for(prop in a){
//assume b doesn't have properties that a hasn't
//only merge on similar types, else keep a
var propA = a[prop],
propB = b[prop];
console.log(prop, typeof propA)
if( (typeof propA == typeof propB) && (typeof propA == "object")){
if(Array.isArray(propA)){
ret[prop] = propA.concat(propB);
}else{
ret[prop] = merge(propA, propB);
}
}else{
ret[prop] = propA;
}
}
return ret;
}
var x = {
name: 'abc',
family: {
children: [
{name: 'xxx'},
{name: 'zzz'}
]
}
};
var y = {
name: 'abc',
family: {
children: [
{name: 'yyy'}
]
}
};
console.log(merge(x, y));
console.log(merge(y, x));
I assume one of your objects is the state you want to change in your reducer.
What about:
return Object.assign({}, x, {
family: [...x.family, ...y.family]
})
First this creates a new empty object and assigns x ( your old state ) to it. Afterwards it assigns the family which it overrides in the new object.
The ... represents all elements in an array, so this can be used to concat the arrays.
This question already has answers here:
Get JavaScript object from array of objects by value of property [duplicate]
(17 answers)
Closed 6 years ago.
I have an array of objects and I wanted to search through each object and check if the data matches a given value and I want to return the object out of the array and if it is not found then I have to return undefined.
This is what I have so far:
var data = [{
id: 1,
firstName: 'John',
lastName: 'Smith'
}, {
id: 2,
firstName: 'Jane',
lastName: 'Smith'
}, {
id: 3,
firstName: 'John',
lastName: 'Doe'
}];
var asf[] = data[0];
return asf;
I'm trying to return the object if the condition in if else statement matches but it gives me error in returning array object.
I am also trying to use _.findwhere(data, pid) which is method in module of underscore can I use it to return the object out of array?
You can use Array.prototype.find(), like this:
var data = [{
id: 1,
firstName: 'John',
lastName: 'Smith'
}, {
id: 2,
firstName: 'Jane',
lastName: 'Smith'
}, {
id: 3,
firstName: 'John',
lastName: 'Doe'
}];
data.find(x => {x.id === 1});
If you like to know more about arrays vist this link.
http://exploringjs.com/es6/ch_arrays.html
I'm not sure if you want to return the object or remove the object so I'll show you how to do both as both are very simple to do.
This is a tidied version of your data:
// this is your data
var data = [{
id: 1,
firstName: 'John',
lastName: 'Smith'
}, {
id: 2,
firstName: 'Jane',
lastName: 'Smith'
}, {
id: 3,
firstName: 'John',
lastName: 'Doe'
}];
This the loop you'll use to return the target object from the array:
// loop through the data array
for(var i = 0; i < data.length; i++) {
// check if the current item is "John Smith"
if(data[i].firstName == "John" && data[i].lastName == "Smith") {
return data[i];
}
// continue with the loop if the current item is not "John Smith"
continue;
}
This snippet does the exact same thing but without the continue:
// loop through the data array
for(var i = 0; i < data.length; i++) {
// check if the current item is "John Smith"
if(data[i].firstName == "John" && data[i].lastName == "Smith") {
return data[i];
}
}
This the loop you'll use to remove the target object from the array:
// loop through the data array
for(var i = 0; i < data.length; i++) {
// check if the current item is "John Smith"
if(data[i].firstName == "John" && data[i].lastName == "Smith") {
delete data[i];
// you can also use Array.prototype.splice() to remove an item from an array:
// data.splice(i, 1);
}
// continue with the loop if the current item is not "John Smith"
continue;
}
This snippet does the exact same thing but without the continue:
// loop through the data array
for(var i = 0; i < data.length; i++) {
// check if the current item is "John Smith"
if(data[i].firstName == "John" && data[i].lastName == "Smith") {
delete data[i];
// you can also use Array.prototype.splice() to remove an item from an array:
// data.splice(i, 1);
}
}
Use this snippet if you are using jQuery, instead of returning or deleting anything you can handle the object however you please inside the jQuery callback function.
In this case, I'll be using console.log(); as an example:
$.each(data, function(i, object) {
if(object.firstName == "John" && object.lastName == "Smith") {
console.log(object);
}
});
Good luck and all the best.
Vanilla JS:
var findWhere = function(key,val,array) {
var o;
array.some(function(object) { return object[key] == val && (o = object); });
return o;
};
var data = []; //your array
findWhere('id',1,data); //get the first object in the array where id = 1
EDIT
Here's a better one that actually takes a callback and can return just one element, or all matching elements:
var find = function(arr,cb,all) {
var o;
if(all) {
return arr.filter(cb);
}
arr.some(function(object) { return cb(object) && (o = object); });
return o;
};
var findAll = function(arr,cb) { return find(arr,cb,true); };
//return the first object in the data array where the id = 1
find(data,function(object) { return object.id == 1 });
//return all objects in the data array where name = 'John'
findAll(data,function(object) { return object.firstName = 'John'; });
I want to cycle through the objects contained in an array and change the properties of each one. If I do this:
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j]);
}
The console should bring up every object in the array, right? But in fact it only displays the first object. if I console log the array outside of the loop, all the objects appear so there's definitely more in there.
Anyway, here's the next problem. How do I access, for example Object1.x in the array, using the loop?
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j.x]);
}
This returns "undefined." Again the console log outside the loop tells me that the objects all have values for "x". How do I access these properties in the loop?
I was recommended elsewhere to use separate arrays for each of the properties, but I want to make sure I've exhausted this avenue first.
Thank you!
Use forEach its a built-in array function. Array.forEach():
yourArray.forEach(function (arrayItem) {
var x = arrayItem.prop1 + 2;
console.log(x);
});
Some use cases of looping through an array in the functional programming way in JavaScript:
1. Just loop through an array
const myArray = [{x:100}, {x:200}, {x:300}];
myArray.forEach((element, index, array) => {
console.log(element.x); // 100, 200, 300
console.log(index); // 0, 1, 2
console.log(array); // same myArray object 3 times
});
Note: Array.prototype.forEach() is not a functional way strictly speaking, as the function it takes as the input parameter is not supposed to return a value, which thus cannot be regarded as a pure function.
2. Check if any of the elements in an array pass a test
const people = [
{name: 'John', age: 23},
{name: 'Andrew', age: 3},
{name: 'Peter', age: 8},
{name: 'Hanna', age: 14},
{name: 'Adam', age: 37}];
const anyAdult = people.some(person => person.age >= 18);
console.log(anyAdult); // true
3. Transform to a new array
const myArray = [{x:100}, {x:200}, {x:300}];
const newArray= myArray.map(element => element.x);
console.log(newArray); // [100, 200, 300]
Note: The map() method creates a new array with the results of calling a provided function on every element in the calling array.
4. Sum up a particular property, and calculate its average
const myArray = [{x:100}, {x:200}, {x:300}];
const sum = myArray.map(element => element.x).reduce((a, b) => a + b, 0);
console.log(sum); // 600 = 0 + 100 + 200 + 300
const average = sum / myArray.length;
console.log(average); // 200
5. Create a new array based on the original but without modifying it
const myArray = [{x:100}, {x:200}, {x:300}];
const newArray= myArray.map(element => {
return {
...element,
x: element.x * 2
};
});
console.log(myArray); // [100, 200, 300]
console.log(newArray); // [200, 400, 600]
6. Count the number of each category
const people = [
{name: 'John', group: 'A'},
{name: 'Andrew', group: 'C'},
{name: 'Peter', group: 'A'},
{name: 'James', group: 'B'},
{name: 'Hanna', group: 'A'},
{name: 'Adam', group: 'B'}];
const groupInfo = people.reduce((groups, person) => {
const {A = 0, B = 0, C = 0} = groups;
if (person.group === 'A') {
return {...groups, A: A + 1};
} else if (person.group === 'B') {
return {...groups, B: B + 1};
} else {
return {...groups, C: C + 1};
}
}, {});
console.log(groupInfo); // {A: 3, C: 1, B: 2}
7. Retrieve a subset of an array based on particular criteria
const myArray = [{x:100}, {x:200}, {x:300}];
const newArray = myArray.filter(element => element.x > 250);
console.log(newArray); // [{x:300}]
Note: The filter() method creates a new array with all elements that pass the test implemented by the provided function.
8. Sort an array
const people = [
{ name: "John", age: 21 },
{ name: "Peter", age: 31 },
{ name: "Andrew", age: 29 },
{ name: "Thomas", age: 25 }
];
let sortByAge = people.sort(function (p1, p2) {
return p1.age - p2.age;
});
console.log(sortByAge);
9. Find an element in an array
const people = [ {name: "john", age:23},
{name: "john", age:43},
{name: "jim", age:101},
{name: "bob", age:67} ];
const john = people.find(person => person.name === 'john');
console.log(john);
The Array.prototype.find() method returns the value of the first element in the array that satisfies the provided testing function.
References
Array.prototype.some()
Array.prototype.forEach()
Array.prototype.map()
Array.prototype.filter()
Array.prototype.sort()
Spread syntax
Array.prototype.find()
You can use a for..of loop to loop over an array of objects.
for (let item of items) {
console.log(item); // Will display contents of the object inside the array
}
One of the best things about for..of loops is that they can iterate over more than just arrays. You can iterate over any type of iterable, including maps and objects. Make sure you use a transpiler or something like TypeScript if you need to support older browsers.
If you wanted to iterate over a map, the syntax is largely the same as the above, except it handles both the key and value.
for (const [key, value] of items) {
console.log(value);
}
I use for..of loops for pretty much every kind of iteration I do in Javascript. Furthermore, one of the coolest things is they also work with async/await as well.
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j].x);
}
Here's an example on how you can do it :)
var students = [{
name: "Mike",
track: "track-a",
achievements: 23,
points: 400,
},
{
name: "james",
track: "track-a",
achievements: 2,
points: 21,
},
]
students.forEach(myFunction);
function myFunction(item, index) {
for (var key in item) {
console.log(item[key])
}
}
Looping through an array of objects is a pretty fundamental functionality. This is what works for me.
var person = [];
person[0] = {
firstName: "John",
lastName: "Doe",
age: 60
};
var i, item;
for (i = 0; i < person.length; i++) {
for (item in person[i]) {
document.write(item + ": " + person[i][item] + "<br>");
}
}
It's really simple using the forEach method since ES5+. You can directly change each property of each object in your array.
myArray.forEach(function (arrayElem){
arrayElem = newPropertyValue;
});
If you want to access a specific property on each object:
myArray.forEach(function (arrayElem){
arrayElem.nameOfYourProperty = newPropertyValue;
});
myArray[j.x] is logically incorrect.
Use (myArray[j].x); instead
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j].x);
}
const jobs = [
{
name: "sipher",
family: "sipherplus",
job: "Devops"
},
{
name: "john",
family: "Doe",
job: "Devops"
},
{
name: "jim",
family: "smith",
job: "Devops"
}
];
const txt =
` <ul>
${jobs.map(job => `<li>${job.name} ${job.family} -> ${job.job}</li>`).join('')}
</ul>`
;
document.body.innerHTML = txt;
Be careful about the back Ticks (`)
this.data = [{name:"Rajiv", city:"Deoria"},{name:"Babbi", city:"Salempr"},{name:"Brijesh", city:"GKP"}];
for(const n of this.data) {
console.log(n.name)
}
This would work. Looping thorough array(yourArray) . Then loop through direct properties of each object (eachObj) .
yourArray.forEach( function (eachObj){
for (var key in eachObj) {
if (eachObj.hasOwnProperty(key)){
console.log(key,eachObj[key]);
}
}
});
Accepted answer uses normal function. So posting the same code with slight modification using arrow function on forEach
yourArray.forEach(arrayItem => {
var x = arrayItem.prop1 + 2;
console.log(x);
});
Also in $.each you can use arrow function like below
$.each(array, (item, index) => {
console.log(index, item);
});
Here's another way of iterating through an array of objects (you need to include jQuery library in your document for these).
$.each(array, function(element) {
// do some operations with each element...
});
Array object iteration, using jQuery,
(use the second parameter to print the string).
$.each(array, function(index, item) {
console.log(index, item);
});
var c = {
myProperty: [
{ name: 'this' },
{ name: 'can' },
{ name: 'get' },
{ name: 'crazy' }
]
};
c.myProperty.forEach(function(myProperty_element) {
var x = myProperty_element.name;
console.log('the name of the member is : ' + x);
})
This is one of the ways how I was able to achieve it.
I want to loop and deconstruction assignment at the same time, so code like this: config.map(({ text, callback })=>add_btn({ text, callback }))
This might help somebody. Maybe it's a bug in Node.
var arr = [ { name: 'a' }, { name: 'b' }, { name: 'c' } ];
var c = 0;
This doesn't work:
while (arr[c].name) { c++; } // TypeError: Cannot read property 'name' of undefined
But this works...
while (arr[c]) { c++; } // Inside the loop arr[c].name works as expected.
This works too...
while ((arr[c]) && (arr[c].name)) { c++; }
BUT simply reversing the order does not work. I'm guessing there's some kind of internal optimization here that breaks Node.
while ((arr[c].name) && (arr[c])) { c++; }
Error says the array is undefined, but it's not :-/ Node v11.15.0
I know it's been long but for anyone else encountering this issue, my problem is that I was looping through an array of arrays containing only one array. Like this:
// array snippet (returned from here)
} else {
callback([results])
}
And I was using the array like this
for(const result of results){
console.log(result.x)
}
As you can see, the array I wanted to iterate over was actually inside another array. removing the square brackets helped. Node JS and MySQL.
I want to cycle through the objects contained in an array and change the properties of each one. If I do this:
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j]);
}
The console should bring up every object in the array, right? But in fact it only displays the first object. if I console log the array outside of the loop, all the objects appear so there's definitely more in there.
Anyway, here's the next problem. How do I access, for example Object1.x in the array, using the loop?
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j.x]);
}
This returns "undefined." Again the console log outside the loop tells me that the objects all have values for "x". How do I access these properties in the loop?
I was recommended elsewhere to use separate arrays for each of the properties, but I want to make sure I've exhausted this avenue first.
Thank you!
Use forEach its a built-in array function. Array.forEach():
yourArray.forEach(function (arrayItem) {
var x = arrayItem.prop1 + 2;
console.log(x);
});
Some use cases of looping through an array in the functional programming way in JavaScript:
1. Just loop through an array
const myArray = [{x:100}, {x:200}, {x:300}];
myArray.forEach((element, index, array) => {
console.log(element.x); // 100, 200, 300
console.log(index); // 0, 1, 2
console.log(array); // same myArray object 3 times
});
Note: Array.prototype.forEach() is not a functional way strictly speaking, as the function it takes as the input parameter is not supposed to return a value, which thus cannot be regarded as a pure function.
2. Check if any of the elements in an array pass a test
const people = [
{name: 'John', age: 23},
{name: 'Andrew', age: 3},
{name: 'Peter', age: 8},
{name: 'Hanna', age: 14},
{name: 'Adam', age: 37}];
const anyAdult = people.some(person => person.age >= 18);
console.log(anyAdult); // true
3. Transform to a new array
const myArray = [{x:100}, {x:200}, {x:300}];
const newArray= myArray.map(element => element.x);
console.log(newArray); // [100, 200, 300]
Note: The map() method creates a new array with the results of calling a provided function on every element in the calling array.
4. Sum up a particular property, and calculate its average
const myArray = [{x:100}, {x:200}, {x:300}];
const sum = myArray.map(element => element.x).reduce((a, b) => a + b, 0);
console.log(sum); // 600 = 0 + 100 + 200 + 300
const average = sum / myArray.length;
console.log(average); // 200
5. Create a new array based on the original but without modifying it
const myArray = [{x:100}, {x:200}, {x:300}];
const newArray= myArray.map(element => {
return {
...element,
x: element.x * 2
};
});
console.log(myArray); // [100, 200, 300]
console.log(newArray); // [200, 400, 600]
6. Count the number of each category
const people = [
{name: 'John', group: 'A'},
{name: 'Andrew', group: 'C'},
{name: 'Peter', group: 'A'},
{name: 'James', group: 'B'},
{name: 'Hanna', group: 'A'},
{name: 'Adam', group: 'B'}];
const groupInfo = people.reduce((groups, person) => {
const {A = 0, B = 0, C = 0} = groups;
if (person.group === 'A') {
return {...groups, A: A + 1};
} else if (person.group === 'B') {
return {...groups, B: B + 1};
} else {
return {...groups, C: C + 1};
}
}, {});
console.log(groupInfo); // {A: 3, C: 1, B: 2}
7. Retrieve a subset of an array based on particular criteria
const myArray = [{x:100}, {x:200}, {x:300}];
const newArray = myArray.filter(element => element.x > 250);
console.log(newArray); // [{x:300}]
Note: The filter() method creates a new array with all elements that pass the test implemented by the provided function.
8. Sort an array
const people = [
{ name: "John", age: 21 },
{ name: "Peter", age: 31 },
{ name: "Andrew", age: 29 },
{ name: "Thomas", age: 25 }
];
let sortByAge = people.sort(function (p1, p2) {
return p1.age - p2.age;
});
console.log(sortByAge);
9. Find an element in an array
const people = [ {name: "john", age:23},
{name: "john", age:43},
{name: "jim", age:101},
{name: "bob", age:67} ];
const john = people.find(person => person.name === 'john');
console.log(john);
The Array.prototype.find() method returns the value of the first element in the array that satisfies the provided testing function.
References
Array.prototype.some()
Array.prototype.forEach()
Array.prototype.map()
Array.prototype.filter()
Array.prototype.sort()
Spread syntax
Array.prototype.find()
You can use a for..of loop to loop over an array of objects.
for (let item of items) {
console.log(item); // Will display contents of the object inside the array
}
One of the best things about for..of loops is that they can iterate over more than just arrays. You can iterate over any type of iterable, including maps and objects. Make sure you use a transpiler or something like TypeScript if you need to support older browsers.
If you wanted to iterate over a map, the syntax is largely the same as the above, except it handles both the key and value.
for (const [key, value] of items) {
console.log(value);
}
I use for..of loops for pretty much every kind of iteration I do in Javascript. Furthermore, one of the coolest things is they also work with async/await as well.
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j].x);
}
Here's an example on how you can do it :)
var students = [{
name: "Mike",
track: "track-a",
achievements: 23,
points: 400,
},
{
name: "james",
track: "track-a",
achievements: 2,
points: 21,
},
]
students.forEach(myFunction);
function myFunction(item, index) {
for (var key in item) {
console.log(item[key])
}
}
Looping through an array of objects is a pretty fundamental functionality. This is what works for me.
var person = [];
person[0] = {
firstName: "John",
lastName: "Doe",
age: 60
};
var i, item;
for (i = 0; i < person.length; i++) {
for (item in person[i]) {
document.write(item + ": " + person[i][item] + "<br>");
}
}
It's really simple using the forEach method since ES5+. You can directly change each property of each object in your array.
myArray.forEach(function (arrayElem){
arrayElem = newPropertyValue;
});
If you want to access a specific property on each object:
myArray.forEach(function (arrayElem){
arrayElem.nameOfYourProperty = newPropertyValue;
});
myArray[j.x] is logically incorrect.
Use (myArray[j].x); instead
for (var j = 0; j < myArray.length; j++){
console.log(myArray[j].x);
}
const jobs = [
{
name: "sipher",
family: "sipherplus",
job: "Devops"
},
{
name: "john",
family: "Doe",
job: "Devops"
},
{
name: "jim",
family: "smith",
job: "Devops"
}
];
const txt =
` <ul>
${jobs.map(job => `<li>${job.name} ${job.family} -> ${job.job}</li>`).join('')}
</ul>`
;
document.body.innerHTML = txt;
Be careful about the back Ticks (`)
this.data = [{name:"Rajiv", city:"Deoria"},{name:"Babbi", city:"Salempr"},{name:"Brijesh", city:"GKP"}];
for(const n of this.data) {
console.log(n.name)
}
This would work. Looping thorough array(yourArray) . Then loop through direct properties of each object (eachObj) .
yourArray.forEach( function (eachObj){
for (var key in eachObj) {
if (eachObj.hasOwnProperty(key)){
console.log(key,eachObj[key]);
}
}
});
Accepted answer uses normal function. So posting the same code with slight modification using arrow function on forEach
yourArray.forEach(arrayItem => {
var x = arrayItem.prop1 + 2;
console.log(x);
});
Also in $.each you can use arrow function like below
$.each(array, (item, index) => {
console.log(index, item);
});
Here's another way of iterating through an array of objects (you need to include jQuery library in your document for these).
$.each(array, function(element) {
// do some operations with each element...
});
Array object iteration, using jQuery,
(use the second parameter to print the string).
$.each(array, function(index, item) {
console.log(index, item);
});
var c = {
myProperty: [
{ name: 'this' },
{ name: 'can' },
{ name: 'get' },
{ name: 'crazy' }
]
};
c.myProperty.forEach(function(myProperty_element) {
var x = myProperty_element.name;
console.log('the name of the member is : ' + x);
})
This is one of the ways how I was able to achieve it.
I want to loop and deconstruction assignment at the same time, so code like this: config.map(({ text, callback })=>add_btn({ text, callback }))
This might help somebody. Maybe it's a bug in Node.
var arr = [ { name: 'a' }, { name: 'b' }, { name: 'c' } ];
var c = 0;
This doesn't work:
while (arr[c].name) { c++; } // TypeError: Cannot read property 'name' of undefined
But this works...
while (arr[c]) { c++; } // Inside the loop arr[c].name works as expected.
This works too...
while ((arr[c]) && (arr[c].name)) { c++; }
BUT simply reversing the order does not work. I'm guessing there's some kind of internal optimization here that breaks Node.
while ((arr[c].name) && (arr[c])) { c++; }
Error says the array is undefined, but it's not :-/ Node v11.15.0
I know it's been long but for anyone else encountering this issue, my problem is that I was looping through an array of arrays containing only one array. Like this:
// array snippet (returned from here)
} else {
callback([results])
}
And I was using the array like this
for(const result of results){
console.log(result.x)
}
As you can see, the array I wanted to iterate over was actually inside another array. removing the square brackets helped. Node JS and MySQL.