Term.BecameEmpty

Syntax

BecameEmpty: function(sender, args);

Parameters

sender. Event source.

args. Information on the event.

Description

The BecameEmpty event occurs after a term becomes empty.

Example

To execute the example, the HTML page must contain links to the PP.js and PP.Ufe.js scenario files and PP.css and PP.Ufe.css styles files in the <body> tag of HTML document of the <div> element with the "termedit" identifier. Create a term editor on the HTML page and add several terms:

function createTerm() {
    // Create a term editor
    termEdit = new PP.Ui.TermEdit({
        // Set parent element
        ParentNode: document.getElementById("termEdit")
    });
    // Add string value to editor
    termEdit.insertString("100");
    // Add data to editor
    termEdit.insertData([new PP.Ui.Term({ Content: "+", Formula: "+" })]);    
    // Add term to editor
    termEdit.insertString("20");
}

As a result several terms are added to the term editor:

Put the cursor to the term with the 20 contents. Get the obtained term and add the BecameEmpty event handler to it, as well, get start and end term positions in the expression and check if the term contains one character:

// Get the selected term
term = termEdit.getSelectedTerm();
// Add the processing of the event of becoming empty to the selected term
term.BecameEmpty.add(function (sender, args) {
    console.log("The selected term became empty");
}, term);
// Get the number of start term position
console.log("Start term position: " + term.getStartOffset());
// Get the number of end term position
console.log("End term position: " + term.getEndOffset());
// Check if the selected term contains one character
if (term.getIsOneCharTerm()) {
    console.log("The selected term contains one character");
} else {
    console.log("The selected term does not contain one character");
}

As a result the console displays the start and end position of the selected term:

Start term position: 4

End term position: 6

The selected term does not contain one character

Check if formula of the selected term can be edited:

// Check if formula of the selected term can be edited
if (term.canEditFormula()) {
    console.log("Term formula can be edited");
} else {
    console.log("Term formula cannot be edited");
}

As a result the console displays check result:

Term formula can be edited

Delete the first and the last term characters:

// Delete the last term character
term.deleteLastChar();
// Delete the first term character
term.deleteFirstChar();
// Refresh editor terms
termEdit.updateTerms();

As a result the term with the 20 contents is missing in the term editor:

The console displays a message that the selected term became empty:

The selected term became empty