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I ran into this line of code and I can't figure out what it means:
$("#theAppContainer")[s > u ? "addClass" : "removeClass"]("something");
I understand the first part is selecting the element called theAppContainer and the second part evaluates to "addClass" if s > u, but I can't figure out what this line of code does overall.
208
It means a table row who has an id that starts with "message": $('tr // a table row [id //having an id ^="message"]') // starting with 'message' http://api.jquery.com/category/selectors/attribute-selectors/ Follow this answer to receive notifications.
$ is pretty commonly used as a selector function in JS. In jQuery the $ function does much more than select things though. You can pass it a selector to get a collection of matching elements from the DOM. You can pass it a function to run when the document is ready (similar to body.
Bracket notation is more expressive than dot notation because it allows a variable to specify all or part of the property name. This is possible because the JavaScript interpreter automatically converts the expression within the square brackets to a string, and then retrieves the corresponding property.
You can see that HTML contains pieces enclosed in angle brackets (' < ' and ' > '), which are also known as the less-than and greater-than symbols. Each of these angle-bracket-enclosed pieces, called a tag, does not appear to the user, but rather gives information about the page's structure.
The bracket syntax gets the value of a property by name, and the parentheses call the function that is the value of that property. It’s equivalent to:
var container = $('#theAppContainer');
if(s > u) {
container.addClass('something');
} else {
container.removeClass('something');
}
Also, please never write code like that. =)
Also also, toggleClass takes a second switch argument that you can use instead:
$('#theAppContainer').toggleClass('something', s > u);
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