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Javascript is one of the most trending and highly paid language in the tech industry right now.In my early days of my career, I struggled with javascript and soon realized that knowledge of implementing a slider or a plugin is not enough and I have to improve my basics to play with javascript. This article nucleus is “Practical Introduction to Javascript“.

Let’s begin with the very basic.

Window vs Document
Window: In very simple words “every tab is a window”. For example, window.close works when we close the tab.
Document: Whatever user see inside the tab is a document. For example, document.ready works when the page is fully loaded.

Alert vs Console.log
One of the worst and irritating way of checking output and debugging is “alert”. Javascript has got “console.log” function which is used to output data in the console of the browser.It has following benefits:

doesn’t freeze web page, it is non-blocking
shows very large output easily
easy to understand and explore insight of javascript objects

Validation
Generally, first thought comes in a fresher mind after hearing validation is form validation but here I explain you about “Variable Validation“. A variable can store form value, a random string, an array, an object or any value. Consider a scenario where we have to validate a variable and confirm that it contains some string value then the process I prefer is follows:

check whether the variable value is undefined or not
check whether the variable value is null or not
check for string length

Below function will solve the above problem with ease.

function checkVariableValue(value) {
	value = value.trim();
	if( typeof value === "undefined" || value == null || value.length == 0 ) {
		return false;
	} else {
		return true;
	}
}

function checkVariableValue(value) {

value = value.trim();

if( typeof value === "undefined" || value == null || value.length == 0 ) {

return false;

} else {

return true;

}

Array vs Object

When i take interviews, 95% of freshers don’t know the difference between javascript arrays and objects and believe me these two are the most used data type in javascript while developing fronted of any application.
Arrays can be “single dimensional only” in javascript. Eg.

var technologies_array = [] // initializing array 
var technologies_object = {} // initializing object 
var technologies = ["js","php","java",".net"]; //initializing array with values
var tech_salaries = {"js":"100k","php":"90k","java":"80k",".net":"70k"}; //initializing object with values

var technologies_array = [] // initializing array

var technologies_object = {} // initializing object

var technologies = ["js","php","java",".net"]; //initializing array with values

var tech_salaries = {"js":"100k","php":"90k","java":"80k",".net":"70k"}; //initializing object with values

Looping

// Looping on arrays
for ( key in technologies ) {
	console.log("Value at "+key+" key is "+technologies[key])
}
//Lopping on objects
for ( property in tech_salaries ) {
	console.log("Salary of "+property+" developer is "+tech_salaries[property])
}

// Looping on arrays

for ( key in technologies ) {

console.log("Value at "+key+" key is "+technologies[key])

}

//Lopping on objects

for ( property in tech_salaries ) {

console.log("Salary of "+property+" developer is "+tech_salaries[property])

}

Adding values to array and object

// adding value to javascript array
technolgies.push("html");
console.log(technologies)
// adding value to javascript object
tech_salaries.html = "60k";
console.log(tech_salaries)

// adding value to javascript array

technolgies.push("html");

console.log(technologies)

// adding value to javascript object

tech_salaries.html = "60k";

console.log(tech_salaries)

Above I explained some of the practical tips of javascript which I thought every newbie must learn to grow and hope these will be helpful for every developer thinking of learning javascript. Got any question, ask me now.

Category: javascript

Javascript: A Practical Introduction