Here is an example of a string:
<br /> <br /> <br />
Sometimes the string can look like this:
<br /> <br />
Or simply like this:
<br />
How can I determine if a string contains only whitespace and br tags using JavaScript? For example: if(/\s*/.test(content)){ }
When checking for whitespace and <br />, you should use an alternation with zero or more repeats, anchored at the start and end:
if(/^(?:\s|<br \/>)*$/.test(content)){ }
This breakdown is as follows:
^ - indicates the start of input(?:...) - a non-capturing group\s - represents any single whitespace character| - signifies an alternation between two options<br \/> - matches the literal string <br /> (escaping the /)* - allows for zero or multiple occurrences of the preceding group$ - marks the end of inputIf there is a possibility that the space or solidus within the tag may be missing, or the space may be repeated, you can modify the regex to:
if(/^(?:\s|<br *\/?>)*$/.test(content)){ }
Adding * after the space allows for zero or multiple spaces; adding ? after the solidus (/) makes it optional.
Please note: The above patterns do not account for attributes on the br tag, such as <br class="foo" />, <br data-foo="bar"/>, etc. Additionally, they match empty strings.
To include attributes while still matching empty strings:
if(/^(?:\s|<br[^>]*>)*$/.test(content)){ }
// Change ----^^^^
To consider attributes and require at least one whitespace or br tag (eliminating empty strings):
if(/^(?:\s|<br[^>]*>)+$/.test(content)){ }
// Change ------- ---^
Consider this sample string:
let text = " <br /> ";
My first step would be to eliminate all whitespace from the input, avoiding the need for the regex to account for it:
let modifiedText = text.replace(/\s/g, '');
//after this modification, modifiedText will only contain "<br/>"
Next, you can use a regex to verify if <br/> is present in the modified text:
let pattern = /^(?:<br\/>)*$/;
let isValid = pattern.test(modifiedText);
"^\s*<br />$"
This code snippet will select all lines that have any amount of whitespace characters at the beginning and end with "
"
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