Stop timer at zero

Question

I am trying to get my countdown to stop at zero however it resets rather than stops.

I've added a conditional statement at the end of the runTimer function but nothing happens. It just resets.

I'm going off of an exercise where it counts up. I'm modifying it a bit and having it countdown.

function runTimer() {
    let currentTime = leadingZero(timer[1]) + ":" + leadingZero(timer[2]);
    theTimer.innerHTML = currentTime;
    timer[3]--;

    timer[0] = Math.floor((timer[3]/100)/60); //minutes
    timer[1] = Math.floor((timer[3]/100) - (timer[0] * 60)); //seconds
    timer[2] = Math.floor(timer[3] - (timer[1] * 100) - (timer[0] * 6000)); //hundredths

    if (currentTime = 0) {
      clearInterval(interval);
    }

}

I expected it to stop at zero but it just resets back to 59:00... and I want it to stop at 00:00.

Answer 1

The problem is this part:

if (currentTime = 0)

Since you're checking if the value is 0, you don't want to assign a value of 0, instead you want to compare currentTime with 0. This is done with the === operator. So to summarize:

= is to assign a value to a variable. ( left is variable and right is the assignment)

== or === is to compare the two values.(Difference between == and === in JavaScript)

Your line should be:

if (currentTime == 0)

Hope it helped. :)

Answer 2

两点。

1）如前所述，您的if子句将不起作用，因为您使用的是“ =”（单个等号）。 JavaScript中的单个等号执行 assign 值，而不执行 compare 值。但是，您需要比较值，并且需要使用双精度或三重等于。

2）即使您进行了更改，currentTime也可能永远不会取值为零，因为您之前已经为currentTime分配了一个字符串。因此，即使currentTime为"00:00"，该字符串也不会计算为0（参见图片）

我想您更想做这样的事情：

if (timer[2] === 0 && timer [1] === 0 && timer[0] === 0) {
    clearInterval(interval);
}

或者最有可能满足以下条件：

if (timer[3] <= 0) {
    clearInterval(interval);
}