Introduction to JavaScript Loop Array
The following article provides an outline for JavaScript Loop Array. In JavaScript we have different set of loops structures and its features are very helpful for creating and validate the web pages for sent the request to the servers. Especially for receiving the response from the servers and it will show in the web page screens. There are different types and ways for JavaScript arrays and it is more complicated to identified which array sequence will be used in the script. Meanwhile the for loop is one of the basic JavaScript loop like that forEach methods and its collections own libraries with forEach and also each of its methods. When we use arrays in the script using iterate method we will retrieve the data.
Syntax:
In JavaScript we use different set of loops in the web page based on the requirements. We will apply it in the scripts but when we validate something on the web page itself its very much helpful for “for,while”etc.
<html>
<head>
<script>
var variable name=””;
//use any loops for example for and while we used in this script
for(inti=initialize value;condition check;increment/decrement)
{
Some logics;
}
while(variablename condition check)
{
--some logics---
}
</script>
</head>
<body>
</body>
</html>
The above code is the basic usages of the loops in JavaScript when we declare arrays in the script using for loop and forEach we can iterate it for retrieving the values.
How does JavaScript Loop Array work?
The JavaScript loops always iterate with the each items in an single array if we use multi-dimensional array we can use forEach or else we will use multiple ordinary for loops to iterate the elements. Basically arrays are zero-based index element which means the first element will start at 0 index and it goes on still the declaration will end. Always reference items in the arrays are specific with numerical index it is also starting with 0 index and ending with the array lengths. We use always for loop statements with three type of expressions like initialize the values declared the conditions and increment/decrement the variable it’s the final type of expressions.
These type of expressions are executed at the end of each loop executions moreover it is used to increment the index if we want to iterate the second level of property or field elements also can be nested with the conditions in the for loops and also main big advantage for to keep the track the elements with separate type of index variables in the script. If we want to stop the execution of the for loop we use break statement or set the index to the array length or the value that will make the script statements has no longer values. Also if we want to omit the conditions in the for loop statement use break keyword to terminate the for loop conditions then the value gets no longer set of the true conditions. The basic for loop condition is easy for to understand the code logics and satisfied the requirements and also it takes more memory consumption when compared to other type of loops because it must satisfy the conditions otherwise the loops are terminated and the syntax also tedious.
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When we used nested for loops it will create and initialize the variables it satisfied all the nested loop conditions and it must be either increment or decrement the variables. If we use forEach loop it first use the native array object for the JavaScript actually forEach loop used callback function in the code it must follow the three type of parameters called element value, element index and array being traversed in the loop element are being current items in the array variable values we use the variable initialization in the loop we must used the initialized variable in the array variable in forEach loop it uses only the element type its not acceptable for the indexes and arrays element is nothing but the values iterating so we should always declare an element that has the parameter type after callback function is executed in forEach loop it also accepts the optional parameter has thisArg keyword we use this keyword for the calling current method or values in the loop count as the variable declaration for counting the values in the particular method in the outside of the scope.
Examples of JavaScript Loop Array
Given below are the examples mentioned:
Example #1
Code:
<!DOCTYPEhtml>
<html>
<body>
<h2>Welcome To My Domain</h2>
<p>Gud day</p>
<p id="demo"></p>
<script>
var t = "";
var n = [34, 41, 76, 2, 13];
n.forEach(sample);
document.getElementById("demo").innerHTML = t;
function sample(v, i, a) {
t = t + v + "<br>";
}
</script>
</body>
</html>
Output:
Example #2
Code:
<html>
<head>
<script language="javascript">
document.writeln("<h2>Welcome To My Domain</h2>");
var b = { "First" : [
{ "Name" : "Sivaraman", "Id" : 2 },
{ "Name" : "Arun", "Id" : 3 }],
"Second" : [
{ "Name" : "Kumar", "Id" : 4 },
{ "Name" : "Saran", "Id" : 5 }]
}
var i = 0
document.writeln("<table border = '3'><tr>");
for(i = 0;i<b.First.length;i++) {
document.writeln("<td>");
document.writeln("<table border = '2' width = 37 >");
document.writeln("<tr><td><b>Name</b></td><td width = 27>" + b.First[i].Name+"</td></tr>");
document.writeln("<tr><td><b>Id</b></td><td width = 57>" + b.First[i].Id +"</td></tr>");
document.writeln("</table>");
document.writeln("</td>");
}
for(i = 0;i<b.Second.length;i++) {
document.writeln("<td>");
document.writeln("<table border = '4' width = 67 >");
document.writeln("<tr><td><b>Name</b></td><td width = 50>" + b.Second[i].Name+"</td></tr>");
document.writeln("<tr><td><b>Id</b></td><td width = 50>" + b.Second[i].Id+"</td></tr>");
document.writeln("</table>");
document.writeln("</td>");
}
document.writeln("</tr></table>");
</script>
</head>
<body>
</body>
</html>
Output:
Example #3
Code:
<!DOCTYPEhtml>
<html>
<body>
<h2>Welcome To My Domain</h2>
<p id="demo"></p>
<script>
var t = ""
var i = 0;
do {
t += "<br>The given number is " + i;
i++;
}
while (i < 10);
document.getElementById("demo").innerHTML = t;
</script>
</body>
</html>
Output:
The above three examples we used the loops in different ways of the JavaScript do, while, for and forEach we have used do while first execute the loops once and after that condition will be checked.
Conclusion
The Looping over arrays is the basic fundamentals of the codes. Basically loops always execute the variable like declared normally or array formats JavaScript has one of the native ways to iterate the arrays and also use libraries to configured.
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