- JavaScript Basics
- JavaScript Tutorial
- JavaScript: where to write
- JavaScript: how to display
- JavaScript: keywords
- JavaScript: comments
- JavaScript: variables
- JavaScript: operators
- JavaScript: data types
- JavaScript Conditional Statements
- JavaScript: if-else
- JavaScript: switch
- JavaScript: for loop
- JavaScript: while loop
- JavaScript: do-while loop
- JavaScript: break and continue
- JavaScript Popup Boxes
- JavaScript: alert box
- JavaScript: confirm box
- JavaScript: prompt box
- JavaScript Popular Topics
- JavaScript: functions
- JavaScript: innerHTML
- JavaScript: getElementById()
- JavaScript: getElementsByClassName()
- JavaScript: getElementsByName()
- JavaScript: getElementsByTagName()
- JavaScript: querySelector()
- JavaScript: querySelectorAll()
- JavaScript: document.write()
- JavaScript: console.log()
- JavaScript: boolean
- JavaScript: events
- JavaScript: Math object
- JavaScript: Math.random()
- JavaScript: Number()
- JavaScript: parseInt()
- JavaScript: parseFloat()
- JavaScript Arrays
- JavaScript: array
- JavaScript: find length of array
- JavaScript: add element at beginning
- JavaScript: add element at end
- JavaScript: remove first element
- JavaScript: remove last element
- JavaScript: get first index
- JavaScript: get last index
- JavaScript: reverse an array
- JavaScript: sort an array
- JavaScript: concatenate arrays
- JavaScript: join()
- JavaScript: toString()
- JavaScript: from()
- JavaScript: check if value exists
- JavaScript: check if array
- JavaScript: slice an array
- JavaScript: splice()
- JavaScript: find()
- JavaScript: findIndex()
- JavaScript: entries()
- JavaScript: every()
- JavaScript: fill()
- JavaScript: filter()
- JavaScript: forEach()
- JavaScript: map()
- JavaScript Strings
- JavaScript: string
- JavaScript: length of string
- JavaScript: convert to lowercase
- JavaScript: convert to uppercase
- JavaScript: string concatenation
- JavaScript: search()
- JavaScript: indexOf()
- JavaScript: search() vs. indexOf()
- JavaScript: match()
- JavaScript: match() vs. search()
- JavaScript: replace()
- JavaScript: toString()
- JavaScript: String()
- JavaScript: includes()
- JavaScript: substr()
- JavaScript: slice string
- JavaScript: charAt()
- JavaScript: repeat()
- JavaScript: split()
- JavaScript: charCodeAt()
- JavaScript: fromCharCode()
- JavaScript: startsWith()
- JavaScript: endsWith()
- JavaScript: trim()
- JavaScript: lastIndexOf()
- JavaScript Date and Time
- JavaScript: date and time
- JavaScript: Date()
- JavaScript: getFullYear()
- JavaScript: getMonth()
- JavaScript: getDate()
- JavaScript: getDay()
- JavaScript: getHours()
- JavaScript: getMinutes()
- JavaScript: getSeconds()
- JavaScript: getMilliseconds()
- JavaScript: getTime()
- JavaScript: getUTCFullYear()
- JavaScript: getUTCMonth()
- JavaScript: getUTCDate()
- JavaScript: getUTCDay()
- JavaScript: getUTCHours()
- JavaScript: getUTCMinutes()
- JavaScript: getUTCSeconds()
- JavaScript: getUTCMilliseconds()
- JavaScript: toDateString()
- JavaScript: toLocaleDateString()
- JavaScript: toLocaleTimeString()
- JavaScript: toLocaleString()
- JavaScript: toUTCString()
- JavaScript: getTimezoneOffset()
- JavaScript: toISOString()
- JavaScript Regular Expression
- JavaScript: regular expression
- JavaScript: RegEx . (dot)
- JavaScript: RegEx \w and \W
- JavaScript: RegEx \d and \D
- JavaScript: RegEx \s and \S
- JavaScript: RegEx \b and \B
- JavaScript: RegEx \0
- JavaScript: RegEx \n
- JavaScript: RegEx \xxx
- JavaScript: RegEx \xdd
- JavaScript: RegEx quantifiers
- JavaScript: RegEx test()
- JavaScript: RegEx lastIndex
- JavaScript: RegEx source
- JavaScript Programs
- JavaScript Programs
JavaScript RegExp test() method
The JavaScript test() method is used when we need to search a string for a match against a regular expression. For example:
<!DOCTYPE html>
<html>
<body>
<p id="res"></p>
<script>
let myString = "I live in St. Louis";
let pattern = /i/;
document.getElementById("res").innerHTML = pattern.test(myString);
</script>
</body>
</html>The pattern /i/ was used to create the regular expression, which matches the letter "i" in a string.
let myString = "I live in St. Louis";
declares and defines the string to be tested. The myString string is passed to the test() method of the regular expression object, which returns a boolean value of true if the pattern is found in the string and false otherwise.
The HTML element with the id "res" then shows the test's outcome. Since the string in this instance contains the pattern /i/, the test's outcome is true, and it will be shown in the paragraph element.
JavaScript test() syntax
The syntax of the test() method in JavaScript is:
RegExpObj.test(x)
where x refers to a string to be searched. The test() method returns a boolean value (true or false). It returns true if a match is available; otherwise, it returns false. For example:
<!DOCTYPE html>
<html>
<body>
<p>Searching for "ive": <span id="resOne"></span></p>
<p>Searching for "ing": <span id="resTwo"></span></p>
<script>
let myString = "I live in St. Louis";
let patternOne = /ive/;
let patternTwo = /ing/;
document.getElementById("resOne").innerHTML = patternOne.test(myString);
document.getElementById("resTwo").innerHTML = patternTwo.test(myString);
</script>
</body>
</html>Searching for "ive":
Searching for "ing":
In the above example, the JavaScript code declares a string variable myString containing the text "I live in St. Louis". It then creates two regular expression patterns patternOne and patternTwo to search for the strings "ive" and "ing" respectively.
The test() method is then called on each pattern and passed the myString variable as an argument. The result of each test() method call, which is a boolean value indicating whether the pattern is found or not in the string, is then assigned to the innerHTML property of two separate HTML elements identified by the resOne and resTwo id attributes respectively.
When the code is executed, it displays the results of both tests in the two HTML elements. If the string "ive" is found in myString, the value true is displayed in the element with the resOne id, and false if not found. Similarly, if the string "ing" is found in myString, the value true is displayed in the element with the resTwo id, and false if not found.
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