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  • FormData
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FormData.append()

The FormData.append() method adds an additional value for an existing entry, if one with that name already exists. If not, it creates a new entry.

Pass in a name and value as arguments.

// Adds an additional "userId" value
data.append('userId', '123');

// Creates a new entry, "tags"
data.append('tags', 'vacations');

Note: Any changes you make happen to the FormData object and its values, not the actual form element or its fields. This method will NOT update the state of the DOM or UI.

Source Code