为什么我的javascript if else语句始终运行第一个选项？

Question

In my code I'm trying to set that if overflow is set to 'visible', it will remove the scrollbars using unloadScrollbars, and when overflow is set to 'hidden' it will not hide the scrollbars. I'm using edge animate (which supports javascript and css), and every time I make an if statement it always executes the first option, whether or not the parameter is true. Please help!

//overrides stage overflow setting
function overflow(toggle) {
    document.getElementById('Stage').style.overflow = toggle;
    return toggle;
}

overflow('hidden');


if (toggle='visible') {
    unloadScrollBars();
    console.log("unloading scrollbars");
} else {
    console.log("not unloading scrollbars");
}

Answer 1

= is an assignment …

if (toggle='visible') {

Is the same as:

toggle='visible';
if (toggle) {

… you want a comparison: == or === .

Answer 2

if (toggle='visible') {

应该

if (toggle=='visible') {

Answer 3

toggle='visible'

This is assignment. (toggle='vivible') is always true in javascript.

toggle == 'visible'

This performs a comparison, with type conversion if needed.

toggle === 'visible'

performs a comparison of variable type and variable content.