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Questions and Answers
What is the purpose of the xhr.send() method?
Which event is triggered periodically while the response is being downloaded and reports how much has been downloaded?
What does the xhr.onerror event trigger?
Which method is used to specify the main parameters of an XMLHttpRequest request?
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What is the difference between synchronous and asynchronous modes of operation in XMLHttpRequest?
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When should XMLHttpRequest be used instead of fetch?
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Which method is used to configure the XMLHttpRequest request, but does not open the connection?
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What does the optional 'body' parameter of the xhr.send() method contain?
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Which event is triggered when the request is complete, even if the HTTP status is like 400 or 500?
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What is the primary reason to use XMLHttpRequest in modern web development?
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What is the difference between synchronous and asynchronous modes of operation in XMLHttpRequest?
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What are the two primary steps to do a request using XMLHttpRequest?
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Study Notes
XMLHttpRequest Methods and Events
- The
xhr.send()method is used to send the request to the server. - The
xhr.onprogressevent is triggered periodically while the response is being downloaded, reporting how much has been downloaded.
Error Handling
- The
xhr.onerrorevent is triggered when an error occurs during the request.
Request Configuration
- The
xhr.open()method is used to specify the main parameters of an XMLHttpRequest request, such as the method, URL, and asynchronous mode. - The
xhr.open()method is used to configure the XMLHttpRequest request, but does not open the connection.
Request Body
- The optional
bodyparameter of thexhr.send()method contains the data to be sent with the request.
Request Completion
- The
xhr.onloadevent is triggered when the request is complete, even if the HTTP status is like 400 or 500.
XMLHttpRequest Usage
- XMLHttpRequest should be used instead of fetch when you need more control over the request, such as setting headers, sending binary data, or tracking progress.
- The primary reason to use XMLHttpRequest in modern web development is to have more control over the request and response.
- The two primary steps to do a request using XMLHttpRequest are:
- Calling the
xhr.open()method to configure the request. - Calling the
xhr.send()method to send the request.
- Calling the
Synchronous and Asynchronous Modes
- In synchronous mode, the script execution is blocked until the request is complete, while in asynchronous mode, the script execution continues, and the request is handled in the background.
- The main difference between synchronous and asynchronous modes of operation in XMLHttpRequest is that synchronous mode blocks the script execution, while asynchronous mode does not.
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Description
Test your knowledge on XMLHttpRequest, an important browser object that enables HTTP requests and data manipulation in JavaScript. Learn about its functionalities and how it compares to the newer fetch method in modern web development.
