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Software Development Terms Beginning with I


An idempotent function produces the same result no matter how many times you pass it to itself.

For instance, suppose invoking myFunction(5) returns 100. In that case, myFunction is idempotent if invoking myFunction(myFunction(5)) also outputs 100.

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if Conditional Statement in JavaScript

The if conditional statement instructs the computer to execute a JavaScript code block only if a specified condition is true.

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Ignore Case (RegExp)

The ignore case flag (i) tells the computer to do a case-insensitive search for a RegExp pattern.

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Immediately Invoked Function Expression (IIFE)

An immediately invoked function expression (IIFE) is a function expression that invokes itself automatically.

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import.meta (ES Module)

The import.meta code is an object containing information about your current module.

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Impure Function

An impure function is a function that contains one or more side effects.

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includes() JavaScript Array Method

includes() checks if its calling array includes the method's first argument.

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includes() JavaScript String Method

includes() checks if its calling string includes the method's first argument.

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Index refers to the position of items.

For instance, an array object's indexing starts at zero. In other words, the index of an array's first item is 0. The second value's index is 1. And the last item's index is the array's length minus 1.

Consider this array object:

["Blue", "White", "Pink", "Green"];

The index (positions) of the array items above are:

  • Blue is at index 0
  • White's index is 1
  • Pink's index is 2
  • Green is at index 3

indexOf() JavaScript Array Method

indexOf() searches its calling array for the first occurrence of the method's string argument.

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indexOf() JavaScript String Method

indexOf() searches its calling string for the first occurrence of the method's string argument.

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Indices (RegExp)

Regular expression's indices flag (d) tells the computer to include each capturing group's start and end indices in the result of the matched RegExp pattern.

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Inheritance refers to a child receiving (inheriting) its parent's features.

JavaScript implements inheritance by allowing objects to inherit another object's prototype property.

For instance, if you use the JavaScript new keyword to create a new object instance. In that case, the newly created object will receive (inherit) its constructor's prototype property.


Initialization occurs when you assign an initial value to a variable.

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Inline CSS

Inline CSS styles an individual HTML element by adding a style attribute on the element's opening tag.

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Inner Function (JavaScript)

An inner function is a function defined inside a block, module, or another function.

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Instance Property in JavaScript

An instance property is a property the new keyword will assign to the object instance it constructs from a constructor function or class.


Instantiation means creating instances of an object from a constructor.

Instructing Language

An instructor directs the action of a page and its contents. For instance, JavaScript is a commanding language that commands the items of an HTML document.


Integers are numbers without decimals.

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Integration Test (TDD)

An integration test is a test written to assess the functionality of a dependent piece of program.

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An interface means connection.

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Internal API Release Policy

An internal API release policy allows publishing APIs for internal use only.

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Internal CSS

Internal CSS styles an HTML page's content by adding an HTML <style> element in the <head> section of the HTML document.

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Internal Hardware

Internal hardware is the internally connected elements of a machine that you will find inside the device's casing.

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The internet is a means through which data get shared between two or more computers.

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Internet Service Provider

An Internet Service Provider (ISP) is a company providing services that connect personal and business devices to the internet.

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Inversion of Control

Inversion of control (IoC) occurs when you transfer the control of your code's execution to a third party.

The IoC programming principle commonly happens while writing a callback program—where you provide your function as an argument to a third-party's function.

For instance, consider the JavaScript code below:

function bestColor(color) {
console.log("My best color is " + color + ".");

setTimeout(bestColor, 3000, "White");

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In the snippet above, setTimeout() is a third-party code that belongs to the browser's Window object. On the other hand, bestColor() is our own code (a code we wrote ourselves).

Now, since we passed our code (bestColor()) as an argument to a third party's code (setTimeout()). It implies that we've transferred the control of our function's execution to setTimeout().

In other words, we inverted the control of bestColor()'s execution from ourselves to the third party. Therefore, setTimeout() has full control to determine how bestColor() will get executed.


Inversion of control could be problematic if you do not design your code with logic to mitigate trust issues.


Invocation means to execute a piece of code.

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An iterable is an object that has a property with a @@iterator key.

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Iteration Statement in JavaScript

An iteration statement is any piece of code that allows you to repeat a program's execution easily and quickly.

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