What common gotchas should a new JavaScript developer be aware of?
JavaScript Tutorial: if-else Statement in JavaScript
This JavaScript tutorial is a step by step guide on JavaScript If Else Statements. Learn how to use If Else in javascript and also JavaScript If Else Statements. if-else Statement in JavaScript. JavaScript's conditional statements: if; if-else; nested-if; if-else-if. These statements allow you to control the flow of your program's execution based upon conditions known only during run time.
Decision Making in programming is similar to decision making in real life. In programming also we face some situations where we want a certain block of code to be executed when some condition is fulfilled.
A programming language uses control statements to control the flow of execution of the program based on certain conditions. These are used to cause the flow of execution to advance and branch based on changes to the state of a program.
JavaScript’s conditional statements:
- if
- if-else
- nested-if
- if-else-if
These statements allow you to control the flow of your program’s execution based upon conditions known only during run time.
- if: if statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.
Syntax:
if(condition)
{
// Statements to execute if
// condition is true
}
Here, condition after evaluation will be either true or false. if statement accepts boolean values – if the value is true then it will execute the block of statements under it.
If we do not provide the curly braces ‘{‘ and ‘}’ after if( condition ) then by default if statement will consider the immediate one statement to be inside its block. For example,
if(condition)
statement1;
statement2;
// Here if the condition is true, if block
// will consider only statement1 to be inside
// its block.
Flow chart:
Example:
<script type = "text/javaScript">
// JavaScript program to illustrate If statement
var i = 10;
if (i > 15)
document.write("10 is less than 15");
// This statement will be executed
// as if considers one statement by default
document.write("I am Not in if");
< /script>
Output:
I am Not in if
- if-else: The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
Syntax:
if (condition)
{
// Executes this block if
// condition is true
}
else
{
// Executes this block if
// condition is false
}
Example:
<script type = "text/javaScript">
// JavaScript program to illustrate If-else statement
var i = 10;
if (i < 15)
document.write("10 is less than 15");
else
document.write("I am Not in if");
< /script>
Output:
i is smaller than 15
- nested-if A nested if is an if statement that is the target of another if or else. Nested if statements means an if statement inside an if statement. Yes, JavaScript allows us to nest if statements within if statements. i.e, we can place an if statement inside another if statement.
Syntax:
if (condition1)
{
// Executes when condition1 is true
if (condition2)
{
// Executes when condition2 is true
}
}
Example:
<script type = "text/javaScript">
// JavaScript program to illustrate nested-if statement
var i = 10;
if (i == 10) {
// First if statement
if (i < 15)
document.write("i is smaller than 15");
// Nested - if statement
// Will only be executed if statement above
// it is true
if (i < 12)
document.write("i is smaller than 12 too");
else
document.write("i is greater than 15");
}
< /script>
Output:
i is smaller than 15
i is smaller than 12 too
- if-else-if ladder Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
if (condition)
statement;
else if (condition)
statement;
.
.
else
statement;
Example:
<script type = "text/javaScript">
// JavaScript program to illustrate nested-if statement
var i = 20;
if (i == 10)
document.wrte("i is 10");
else if (i == 15)
document.wrte("i is 15");
else if (i == 20)
document.wrte("i is 20");
else
document.wrte("i is not present");
< /script>
Output:
i is 20
How to Retrieve full Profile of LinkedIn User using Javascript
I am trying to retrieve the full profile (especially job history and educational qualifications) of a linkedin user via the Javascript (Fetch LinkedIn Data Using JavaScript)
Here we are fetching LinkedIn data like Username, Email and other fields using JavaScript SDK.
Here we have 2 workarounds.
- Configuration of linkedIn developer api
- Javascript Code to fetch records
Configuration of linkedIn developer api
In order to fetch records, first we need to create developer api in linkedin which will act as token/identity while fetching data from other linkedin accounts.
So to create api, navigate to https://linkedin.com/developer/apps and click on 'Create Application'.
After navigating, fill in details like name, description and other required fields and then submit.
As we submit, it will create Client ID and Client Secret shown below, which we will be using in our code while communicating to fetch records from other LinkedIn account.
Note: We need to provide localhost Url here under Oauth 2.0. I am using my localhost, but you can probably use other production URLs under Oauth 2.0 where your app is configured. It will make your api consider the Url as trusted which fetching records.
Javascript Code to fetch records
For getting user details like first name, last name,User image can be written as,
<script type="text/javascript" src="https://platform.linkedin.com/in.js">
api_key: XXXXXXX //Client ID
onLoad: OnLinkedInFrameworkLoad //Method that will be called on page load
authorize: true
</script>
<script type="text/javascript">
function OnLinkedInFrameworkLoad() {
IN.Event.on(IN, "auth", OnLinkedInAuth);
}
function OnLinkedInAuth() {
IN.API.Profile("me").result(ShowProfileData);
}
function ShowProfileData(profiles) {
var member = profiles.values[0];
var id = member.id;
var firstName = member.firstName;
var lastName = member.lastName;
var photo = member.pictureUrl;
var headline = member.headline;
//use information captured above
var stringToBind = "<p>First Name: " + firstName + " <p/><p> Last Name: " + lastName + "<p/><p>User ID: " + id + " and Head Line Provided: " + headline + "<p/>"
document.getElementById('profiles').innerHTML = stringToBind;
}
</script>
Kindly note we need to include 'https://platform.linkedin.com/in.js' as src under script type as it will act on this Javascript SDK provided by Linkedin.
In the same way we can also fetch records of any organization with the companyid as keyword.
<head>
<script type="text/javascript" src="https://platform.linkedin.com/in.js">
api_key: XXXXXXX ////Client ID
onLoad: onLinkedInLoad
authorize: true
</script>
</head>
<body>
<div id="displayUpdates"></div>
<script type="text/javascript">
function onLinkedInLoad() {
IN.Event.on(IN, "auth", onLinkedInAuth);
console.log("On auth");
}
function onLinkedInAuth() {
var cpnyID = XXXXX; //the Company ID for which we want updates
IN.API.Raw("/companies/" + cpnyID + "/updates?event-type=status-update&start=0&count=10&format=json").result(displayCompanyUpdates);
console.log("After auth");
}
function displayCompanyUpdates(result) {
var div = document.getElementById("displayUpdates");
var el = "<ul>";
var resValues = result.values;
for (var i in resValues) {
var share = resValues[i].updateContent.companyStatusUpdate.share;
var isContent = share.content;
var isTitled = isContent,
isLinked = isContent,
isDescription = isContent,
isThumbnail = isContent,
isComment = isContent;
if (isTitled) {
var title = isContent.title;
} else {
var title = "News headline";
}
var comment = share.comment;
if (isLinked) {
var link = isContent.shortenedUrl;
} else {
var link = "#";
}
if (isDescription) {
var description = isContent.description;
} else {
var description = "No description";
}
/*
if (isThumbnailz) {
var thumbnailUrl = isContent.thumbnailUrl;
} else {
var thumbnailUrl = "http://placehold.it/60x60";
}
*/
if (share) {
var content = "<a target='_blank' href=" + link + ">" + comment + "</a><br>";
//el += "<li><img src='" + thumbnailUrl + "' alt=''>" + content + "</li>";
el += "<li><div>" + content + "</div></li>";
}
console.log(share);
}
el += "</ul>";
document.getElementById("displayUpdates").innerHTML = el;
}
</script>
</body>
We can get multiple metadata while fetching records for any any organization. We can get company updates as shown below.
Conclusion
We can also fetch any company specific data like company job updates/post, total likes, comments, and number of views along with a lot of metadata we can fetch which I have shown below.
Thank you for reading !
7 Best Javascript Iframe Libraries
Iframes let you build user experiences into embeddable ‘cross-domain components’, which let users interact with other sites without being redirected. I have compiled 7 best Javascript iframe libraries.
Iframes let you build user experiences into embeddable ‘cross-domain components’, which let users interact with other sites without being redirected. I have compiled 7 best Javascript iframe libraries.
1. ZoidA cross-domain component toolkit, supporting:
- Render an iframe or popup on a different domain, and pass down props, including objects and functions
- Call callbacks natively from the child window without worrying about post-messaging or cross-domain restrictions
- Create and expose components to share functionality from your site to others!
- Render your component directly as a React, Vue or Angular component!
It's 'data-down, actions up' style components, but 100% cross-domain using iframes and popups!
2. Postmate
Postmate is a promise-based API built on postMessage. It allows a parent page to speak with a child iFrame across origins with minimal effort.
3. Iframe Resizer
Keep same and cross domain iFrames sized to their content with support for window/content resizing, in page links, nesting and multiple iFrames
4. Iframely
Embed proxy. Supports over 1800 domains via custom parsers, oEmbed, Twitter Cards and Open Graph
5. React Frame component
This component allows you to encapsulate your entire React application or per component in an iFrame.
6. Seamless.js
A seamless iframe makes it so that visitors are unable to distinguish between content within the iframe and content beside the iframe. Seamless.js is a JavaScript library (with no dependencies) that makes working with iframes easy by doing all the seamless stuff for you automatically.
7. Porthole
A proxy to safely communicate to cross-domain iframes in javascript
Thank for read!