How to concat string properties of an array in an array of arrays and create a new property in each array

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I have an array of arrays which looks like below:

UserList=[
[name:"user1", type:"admin", location:"NY", expired:"NO"],
[name:"user2", type:"poweruser", location:"CO", expired:"NO"],
[name:"user3", type:"admin", location:"SF", expired:"NO"],
]

I want to add the three properties name, type and location and create a new property in each individual array like the property "AllProps" in the below example:

Desired Output:

UserList=[
[name:"user1", type:"admin", location:"NY", expired:"NO",AllProps:"user1adminNY"],
[name:"user2", type:"poweruser", location:"CO", expired:"NO",AllProps:"user1poweruserCO"],
[name:"user3", type:"admin", location:"SF", expired:"NO", AllProps:"user1adminSF"],
]

Can I do this using Loadash? What is the best and fastest way to do this?

Based on your requirements and wanting to just modify your existing array without return a new one, simply iterate the array and add the key/value pair:

var UserList = [
	{name: "user1", type: "admin", location: "NY", expired: "NO"},
	{name: "user2", type: "poweruser", location: "CO", expired: "NO"},
	{name: "user3", type: "admin", location: "SF", expired: "NO"},
];

UserList.forEach(function(x){
	x["AllProps"] = x.name + x.type + x.location;
});	

console.log(UserList);

Flattening Arrays (The GNU Awk User's Guide), How to concat string properties of an array in an array of arrays and create a new property in each array. 105. April 25, 2018, at 07:49 AM. I have an array of  The concat method creates a new array consisting of the elements in the object on which it is called, followed in order by, for each argument, the elements of that argument (if the argument is an array) or the argument itself (if the argument is not an array). It does not recurse into nested array arguments.

You are using {} but it should be [] for array. Also you need to use : instead of = in objects

var userList= [
{name: "user1", type: "admin", location: "NY", expired: "NO"},
{name: "user2", type: "poweruser", location: "CO", expired: "NO"},
{name: "user3", type: "admin", location: "SF", expired: "NO"}
];

var output = userList.map(user => {
   user.AllProps = user.name + user.type + user.location;
   return user;
});

// Short hand
var output = userList.map(user => ({ ...user, AllProps: user.name + user.type + user.location}));

console.log('output:', output);

Array.prototype.concat(), The concat() method is used to merge two or more arrays. If all valueN parameters are omitted, concat returns a shallow copy of the The concat method creates a new array consisting of the elements in the object concat copies the values of strings and numbers into the new array. Object; Properties. concat() Merge two or more arrays, and returns a new array. copyWithin() Copies part of an array to another location in the same array and returns it. entries() Returns a key/value pair Array Iteration Object. every() Checks if every element in an array pass a test in a testing function. fill() Fill the elements in an array with a static value. filter()

I think something like this is that you need:

_.forEach(UserList, function(u){
  var allPropValues = "";
  _.forOwn(u, function(value, key) {
     if(key !== 'expired') {
        allPropValues += value;
     }
  });  
  u.AllProps = allPropValues;
});

var UserList=[
{name:"user1", type:"admin", location:"NY", expired:"NO"},
{name:"user2", type:"poweruser", location:"CO", expired:"NO"},
{name:"user3", type:"admin", location:"SF", expired:"NO"},
];
console.log({before: UserList});

_.forEach(UserList, function(u){
  var allPropValues = "";
  _.forOwn(u, function(value, key) {
     if(key !== 'expired') {
        allPropValues += value;
     }
  });  
  u.AllProps = allPropValues;
});

console.log({after: UserList});
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.9/lodash.js"></script>

Data Structures: Objects and Arrays :: Eloquent JavaScript, Both string and array values contain, in addition to the length property, There's an Object.assign function that copies all properties from one object into another. The concat method can be used to glue arrays together to create a new array,  When your array is a collection of string or integers (value types), sometimes you will want to update the values in the array as you loop over them. Most of the loops above use a variable in the loop that holds a copy of the value. If you update that variable, the original value in the array is not updated.

Array methods, But for arrays we usually want the rest of elements to shift and occupy the freed place. The method arr.concat creates a new array that includes values from other isConcatSpreadable property, then it's treated as an array by concat : its Literally, all elements are converted to strings for comparisons. String arrays. We begin with string arrays. Square brackets are used for all arrays. The syntax is simple and easy to remember (with practice). Version 1: This code creates a string array of 3 elements, and then assign strings to the array indexes (starting at 0).

Arrays, We can't insert a new property “between” the existing ones. There are two syntaxes for creating an empty array: Append the element to the end of the array: The loop for..in iterates over all properties, not only the numeric ones. to a string, it converts it to a string as well, so the next step looks like this:. Author policies for array properties on Azure resources. Azure Resource Manager properties are commonly defined as strings and booleans. When a one-to-many relationship exists, complex properties are instead defined as arrays.

JavaScript Array Properties and Methods, The following table lists the standard methods of the Array object. Method, Description. concat(), Merge two or more arrays, and returns a new array. If the only argument passed to the Array constructor is an integer between 0 and 2 32-1 (inclusive), this returns a new JavaScript array with its length property set to that number (Note: this implies an array of arrayLength empty slots, not slots with actual undefined values).