问题在于变量i成为闭包的一部分，并且在执行函数时已经等于100.

The issue is that variable i becomes the part of the closure and, when the function is executed, is already equal to 100.

您当前使用的代码实际上会创建一百个引用同一变量(全局i)的超时.到执行所有功能时，i等于100，因此您将100作为当前进度报告为100.

The code you have currently literally creates a hundred of timeouts referencing the same variable(global i). By the time all of the functions are executed, i equals 100, therefore you report 100 as current progress 100 times.

正确的版本应如下所示:

The proper version should look like that:

function run() {
    var i = 0;
    setTimeout( function updateProgress() {
        $("#progressbar").reportprogress(i++);
        if (i < 100){
            setTimeout(updateProgress, 500);
        }
    }, 500);
}

您可以检查javascript花园的闭包部分，以获取解释和可能的其他信息解决方案.

You could check closures part of javascript garden for explanation and possible other solutions.