Javascript 未捕获的类型错误：.indexOf 不是函数

Uncaught TypeError: .indexOf is not a function

提问by TerryO

I am new to JavaScript and I'm getting an erroras below.

我是 JavaScript 新手，出现如下错误。

Uncaught TypeError: time.indexOf is not a function

未捕获的类型错误：time.indexOf 不是函数

Gee, I really thought indexOf() really was a function. Here is a snippet of my code:

哎呀，我真的以为 indexOf() 真的是一个函数。这是我的代码片段：

    var timeofday = new Date().getHours() + (new Date().getMinutes()) / 60;
    document.getElementById("oset").innerHTML = timeD2C(timeofday);
</script>


<script>
 function timeD2C(time) { // Converts 11.5 (decimal) to 11:30 (colon)
    var pos = time.indexOf('.');
    var hrs = time.substr(1, pos - 1);
    var min = (time.substr(pos, 2)) * 60;

    if (hrs > 11) {
        hrs = (hrs - 12) + ":" + min + " PM";
    } else {
        hrs += ":" + min + " AM";
    }
    return hrs;
}
</script>

回答by Rajaprabhu Aravindasamy

Basically indexOf()is a method belongs to string(array object also), But while calling the function you are passing a number, try to cast it to a string and pass it.

基本上indexOf()是一个属于字符串的方法（也是数组对象），但是在调用传递数字的函数时，尝试将其转换为字符串并传递它。

document.getElementById("oset").innerHTML = timeD2C(timeofday + "");

 var timeofday = new Date().getHours() + (new Date().getMinutes()) / 60;




 function timeD2C(time) { // Converts 11.5 (decimal) to 11:30 (colon)
    var pos = time.indexOf('.');
    var hrs = time.substr(1, pos - 1);
    var min = (time.substr(pos, 2)) * 60;

    if (hrs > 11) {
        hrs = (hrs - 12) + ":" + min + " PM";
    } else {
        hrs += ":" + min + " AM";
    }
    return hrs;
}
alert(timeD2C(timeofday+""));

---

---

And it is good to do the string conversion inside your function definition,

最好在函数定义中进行字符串转换，

function timeD2C(time) { 
  time = time + "";
  var pos = time.indexOf('.');

So that the code flow won't break at times when devs forget to pass a string into this function.

这样当开发人员忘记将字符串传递给此函数时，代码流不会中断。

回答by brk

Convert timeofday to string to use indexOf

将 timeofday 转换为要使用的字符串 indexOf

var timeofday = new Date().getHours() + (new Date().getMinutes()) / 60;
console.log(typeof(timeofday)) // for testing will log number
function timeD2C(time) { // Converts 11.5 (decimal) to 11:30 (colon)
    var pos = time.indexOf('.');
    var hrs = time.substr(1, pos - 1);
    var min = (time.substr(pos, 2)) * 60;

    if (hrs > 11) {
        hrs = (hrs - 12) + ":" + min + " PM";
    } else {
        hrs += ":" + min + " AM";
    }
    return hrs;
}
 // "" for typecasting to string
 document.getElementById("oset").innerHTML = timeD2C(""+timeofday);

Test Here

在这里测试

Solution 2

解决方案2

use toString()to convert to string

用于toString()转换为string

document.getElementById("oset").innerHTML = timeD2C(timeofday.toString());

jsfiddle with toString()

jsfiddle 与 toString()

回答by Andrew Grothe

I ran across this error recently using a javascript library which changes the parameters of a function based on conditions.

我最近使用 javascript 库遇到了这个错误，该库根据条件更改函数的参数。

You can test an object to see if it has the function. I would only do this in scenarios where you don't control what is getting passed to you.

您可以测试一个对象以查看它是否具有该功能。我只会在您无法控制传递给您的内容的情况下执行此操作。

if( param.indexOf != undefined ) {
   // we have a string or other object that 
   // happens to have a function named indexOf
}

You can test this in your browser console:

您可以在浏览器控制台中对此进行测试：

> (3).indexOf == undefined;
true

> "".indexOf == undefined;
false