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JavaScript Strings and Text Processing

Working with Textual Data Effectively

Strings are for storing text. Strings are written with quotes.

Using Quotes

A JavaScript string is zero or more characters written inside quotes.

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You can use single or double quotes:

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Strings created with single or double quotes works the same. There is no difference between the two.

Quotes Inside Quotes

You can use quotes inside a string, as long as they don’t match the quotes surrounding the string:

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Template Strings

Templates were introduced with ES6 (JavaScript 2016). Templates are strings enclosed in backticks (This is a template string). Templates allow single and double quotes inside a string:

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Templates are not supported in Internet Explorer.

String Length

To find the length of a string, use the built-in length property:

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Escape Characters

Because strings must be written within quotes, JavaScript will misunderstand this string:

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The string will be chopped to "We are the so-called ". To solve this problem, you can use an backslash escape character. The backslash escape character (\) turns special characters into string characters:

CodeResultDescription
\''Single quote
\""Double quote
\\\Backslash

Examples

\” inserts a double quote in a string:

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\' inserts a single quote in a string:

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Six other escape sequences are valid in JavaScript:

CodeResult
\bbackspace
\fform feed
\nnew line
\rcarriage return
\t horizontal tabulator
\v vertical tabulator
The 6 escape characters above were originally designed to control typewriters, teletypes, and fax machines. They do not make any sense in HTML.

Breaking Long Lines

For readability, programmers often like to avoid long code lines. A safe way to break up a statement is after an operator:

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A safe way to break up a string is by using string addition:

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Template Strings

Templates were introduced with ES6 (JavaScript 2016). Templates are strings enclosed in backticks (This is a template string). Templates allow multiline strings:

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JavaScript Strings as Objects

Normally, JavaScript strings are primitive values, created from literals:

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But strings can also be defined as objects with the keyword new:

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Do not create Strings objects. The new keyword complicates the code and slows down execution speed. String objects can produce unexpected results. When using the == operator, x and y are equal:

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When using the === operator, x and y are not equal:

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Note the difference between (x==y) and (x===y). (x == y) true or false ?

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(x === y) true or false?

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