Var used before declaration

This warning category is spelled [var-used-before-declaration] by qmllint.

Variable is used here before its declaration

You used a variable before you declared it.

This makes the code harder to read. Variables declared with let or const will error out at runtime.

import QtQuick
Item {
    function f() {
        x = 42; // x is used before its declaration
        let x;
    }
    Component.onCompleted: f()
}

To fix this warning, move the declaration before the usage:

import QtQuick
Item {
    function f() {
        let x;
        x = 42;
    }
    Component.onCompleted: f()
}

另请参阅 在 QML 文档中的 JavaScript 表达式 .