Understanding this JavaScript code involving shorthand if statements and commas can be achieved by breaking it down step by

Question

Understanding this JavaScript code involving shorthand if statements and commas can be achieved by breaking it down step by

Upon encountering this function within the codebase (which is compiled with webpack), my curiosity was piqued and I wanted to delve into its workings.

Initially, my eyes fell upon t.length > 100. If it's greater than 100, then the next condition is evaluated. However, this subsequent condition involves the use of , signs which left me puzzled about their purpose.

This snippet unfolds into two distinct parts: $(this).val(t.substring(0, 99)) , e = $(this).val().length

I presume that this is somewhat like a bundled code segment executed as part of a conditional statement without impacting the return value?

function() {
  const t = $(this).val();
  let e = t.length;
  t.length > 100 && 
  (
    $(this).val(t.substring(0, 99)),
    e = $(this).val().length
  ),
  $(this).is("input:text") 
    ? $(".limit_text:visible").text(e) 
    : $(".limit_description:visible").text(e)
}

Considering this, would both codes achieve the same outcome?

function() {
  const t = $(this).val();
  let e = t.length;
  if (t.length > 100) {
    $(this).val(t.substring(0, 99));
    e = $(this).val().length
  }
  $(this).is("input:text") 
    ? $(".limit_text:visible").text(e) 
    : $(".limit_description:visible").text(e)
}

Hence, is , equivalent to ; in this context?

javascript

Answer 1

Answer №1

Within JavaScript, the comma and semicolon have distinct roles. The provided code utilizes the comma as an operator within a conditional statement. It permits multiple expressions to be assessed sequentially, with the final expression determining the overall value of the statement. Specifically:

t.length > 100 && ($(this).val(t.substring(0, 99)), e = $(this).val().length)

The comma operator here splits two expressions enclosed in parentheses. The first expression, $(this).val(t.substring(0, 99)), modifies the value of $(this) (assumedly an input element) to a substring of its existing value. Subsequently, the second expression, e = $(this).val().length, assigns the length of the altered value to variable e. If t.length > 100 is true, both expressions are executed.

In contrast, in the alternative code offered, semicolons (;) are employed instead of the comma operator to separate discrete statements inside the if block. The comparable revised code would appear as follows:

if (t.length > 100) {
    $(this).val(t.substring(0, 99));
    e = $(this).val().length;
}

Answer 2

Within JavaScript, the comma and semicolon have distinct roles. The provided code utilizes the comma as an operator within a conditional statement. It permits multiple expressions to be assessed sequentially, with the final expression determining the overall value of the statement. Specifically:

t.length > 100 && ($(this).val(t.substring(0, 99)), e = $(this).val().length)

The comma operator here splits two expressions enclosed in parentheses. The first expression, $(this).val(t.substring(0, 99)), modifies the value of $(this) (assumedly an input element) to a substring of its existing value. Subsequently, the second expression, e = $(this).val().length, assigns the length of the altered value to variable e. If t.length > 100 is true, both expressions are executed.

In contrast, in the alternative code offered, semicolons (;) are employed instead of the comma operator to separate discrete statements inside the if block. The comparable revised code would appear as follows:

if (t.length > 100) {
    $(this).val(t.substring(0, 99));
    e = $(this).val().length;
}

Answer 3

Answer №2

In the world of JavaScript, it's important to understand that the comma (,) and semicolon (;) are distinct characters with different purposes. However, there are scenarios where they can be used interchangeably.

The first snippet of code showcases how the comma (,) acts as an operator, allowing you to combine multiple expressions by evaluating each one from left to right and ultimately returning the final expression's value. Here, the comma is effectively used to execute two statements enclosed within parentheses as a single expression.

Within this context, the initial statement modifies the input field's value to display only the first 99 characters of the original input through $(this).val(t.substring(0, 99)). Following this, the subsequent statement e = $(this).val().length updates the variable e with the new length of the input field.

On the other hand, the semicolon (;) serves as a definitive statement terminator. The second code snippet mirrors the functionality of the first code block but includes an if statement to evaluate a condition and delimits the two statements using semicolons.

Answer 4

In the world of JavaScript, it's important to understand that the comma (,) and semicolon (;) are distinct characters with different purposes. However, there are scenarios where they can be used interchangeably.

The first snippet of code showcases how the comma (,) acts as an operator, allowing you to combine multiple expressions by evaluating each one from left to right and ultimately returning the final expression's value. Here, the comma is effectively used to execute two statements enclosed within parentheses as a single expression.

Within this context, the initial statement modifies the input field's value to display only the first 99 characters of the original input through $(this).val(t.substring(0, 99)). Following this, the subsequent statement e = $(this).val().length updates the variable e with the new length of the input field.

On the other hand, the semicolon (;) serves as a definitive statement terminator. The second code snippet mirrors the functionality of the first code block but includes an if statement to evaluate a condition and delimits the two statements using semicolons.

Understanding this JavaScript code involving shorthand if statements and commas can be achieved by breaking it down step by

Answer №1

Answer №2

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