Ngfor angular

In this example, we are creating an item using the let keyword of the friendlist array. It will iterate over each item in the array, and will print out the item name and item ngfor angular, or any other object key we have in the array object, ngfor angular. You will see the above output when you save. That is because we have 8 items in the array.

NgFor is a structural directive, meaning that it changes the structure of the DOM. Sometimes we also want to get the index of the item in the array we are iterating over. We can do this by adding another variable to our ngFor expression and making it equal to index , like so:. If our data structure was in fact grouped by country we can use two ngFor directives, like so:. We use the NgFor directive to loop over an array of items and create multiple elements dynamically from a template element.

Ngfor angular

In this post we are going to go over the ngFor core directive, namely we are going to go over the following:. So let's get started diving into ngFor! Below you can also find a video version of this post if you prefer, and the running code of this post is available here. Note: If instead of ngIf you are looking for the for syntax, then check my other guide instead: Angular for: Complete Guide. The core directive ngFor allows us to build data presentation lists and tables in our HTML templates. Let's take for example the following data:. With ngFor we can print this data to the screen under the form of a data table, by generating HTML similar to this:. This template will generate the HTML table that we showed just above. We can see in this example the most common syntax for using ngFor :. Note that the loop variable hero is only visible inside the loop, you would not be able to access it outside the ngFor section. If you have an AngularJs background, you will see this error a few times before you get used to the new Angular syntax:. This is because you have accidentally either used item in items instead of item of items , or forgot to add the let keyword at the beginning of the expression:. A very common requirement is to add to a list the numeric index position of its element. We can get the index of the current element by using the index variable:.

But it is static data, ngfor angular, so let's change it to dynamic. This will change the value of hideList to false from true. Know how to get the index in the array of the item you ngfor angular looping over.

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We will discover, how we can use the ngFor directive to display multiple elements directly from a JavaScript array. Also, we will take a look at the utilities of the ngFor directive, like the index, or even and odd. When we got the basics, we will move on to some more advanced topics like change-detection and DOM manipulation to tweak the performance of our for-loop using trackBy. We can use this directive, if we want to display a dynamic list, for example, an array of elements on the screen. This array could look like this example data:. That array could be static and look like the array above or could be filled at runtime. So to create a list-element for each array element, we place the ngFor directive inside of the li tag. Did you notice that the syntax looks like a regular forEach loop? Well, actually it works quite the same way.

Ngfor angular

In this example, we are creating an item using the let keyword of the friendlist array. It will iterate over each item in the array, and will print out the item name and item age, or any other object key we have in the array object. You will see the above output when you save. That is because we have 8 items in the array. So, we we get 8 items in our list tag.

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I build projects to learn how code works. You will see the above output when you save. Search Submit your search query. Know how to nest multiple NgFor directives together. Nishant Kumar. Is ngFor only For Arrays? If you are just getting started learning Angular, have a look at the Angular for Beginners Course :. This is called interpolation, and it's how we show data in the HTML template. We need to pass a function to trackBy , and the function takes a couple of arguments, which are an index and the current item:. Common ngFor Errors to watch out for If you have an AngularJs background, you will see this error a few times before you get used to the new Angular syntax: Can't bind to 'ngFor' since it isn't a known property of 'tr' This is because you have accidentally either used item in items instead of item of items , or forgot to add the let keyword at the beginning of the expression: Finding the index of a list element A very common requirement is to add to a list the numeric index position of its element. Note that the loop variable hero is only visible inside the loop, you would not be able to access it outside the ngFor section.

NgFor is a structural directive, meaning that it changes the structure of the DOM. Sometimes we also want to get the index of the item in the array we are iterating over.

Let's take for example the following data:. Below you can also find a video version of this post if you prefer, and the running code of this post is available here. In other words, this function will toggle the value of isVisible. Let's say that you are shipping to ancient mobile browsers or ancient versions of IE: you might want to consider applying trackBy as a precaution in your larger tables, but it really depends on your system and the use case. Also, when we pass to ngFor a new list, this does not mean that the whole list will be re-built, meaning all the DOM re-created. There are tons of things you can do. If our data structure was in fact grouped by country we can use two ngFor directives, like so:. Summary We use the NgFor directive to loop over an array of items and create multiple elements dynamically from a template element. So, every time the button is clicked, this function will run. So, we we get 8 items in our list tag. Sometimes we also want to get the index of the item in the array we are iterating over. In order to take that decision Angular needs to identify each list element in a unique way, because for example if we pass in a new list with a different order, Angular will try to identify the elements and re-order the DOM elements of the list without deleting them and recreating them. Note The index is always zero based, so starts at 0 then 1,2,3,4 etc…. Grouping If our data structure was in fact grouped by country we can use two ngFor directives, like so:. So let's get started diving into ngFor!