该函数只被调用一次 [英] the function gets called only once

问题描述

我在html-image上调用了一个简单的函数点击来改变图片。但是，当我重新点击同一图像时，它不会变回同一图像。请帮忙解决： -

i have called a simple function on html-image click to change the pic. But when i re-click on the same image , it does not changes back to the same image. please help in solving :-

function ChangePic() {
            if (document.getElementById("bulb").src = "IMAGES/pic_bulboff.gif")
             document.getElementById("bulb").src = "IMAGES/pic_bulbon.gif";
            else 
           document.getElementById("bulb").src = "IMAGES/pic_bulboff.gif";
            }

<img id="bulb" alt="no pic is available" />

推荐答案

与调用函数一次或两次无关。在你的所有行中，你做作业，你永远不会检查会返回错误的条件。

Javascript条件运算符是'=='，而不是'= '。要修改代码，请考虑更改if运算符的行：将'='替换为'=='。

-SA

It is not related to calling a function once or twice. In all of your lines, you do assignments, you never check up condition which would return false.
Javascript conditional operator is '==', not '='. To fix your code, consider changing the line of your "if" operator: replace '=' by '=='.

—SA

function ChangePic()
       {
           if (document.getElementById("bulb").src== "http://localhost:1620/IMAGES/pic_bulboff.gif")
           document.getElementById("bulb").src = "IMAGES/pic_bulbon.gif";
             else
           document.getElementById("bulb").src = "IMAGES/pic_bulboff.gif";
         }

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