includes() not working in all browsers

问题:

right here is a block of my code. It works perfect in fireFox and Chrome. But not in IE. I get the error "Object doesn't support property or method 'includes'"

function rightTreeSwapfunc2() {
    if ($(".right-tree").css("background-image").includes("stage1") == true) {
        $(".right-tree").css({
            backgroundImage: "url(/plant-breeding/img/scenes/plant-breeding/stage5.jpg)"
        })
    } else {
        $(".right-tree").css({
            backgroundImage: "url(/plant-breeding/img/scenes/plant-breeding/stage3.jpg)"
        })
    }
}

I could change it up a bit and use vanilla JS and do:

document.getElementById("right-tree").classList.contains

But I would rather see if there is a way to get it to work in IE before changing the JS and editing the HTML and CSS.

回答1:

If you look at the documentation of includes(), most of the browsers don't support this property.

You can use widely supported indexOf() after converting the property to string using toString():

if ($(".right-tree").css("background-image").indexOf("stage1") > -1) {
//                                           ^^^^^^^^^^^^^^^^^^^^^^

You can also use the polyfill from MDN.

if (!String.prototype.includes) {
    String.prototype.includes = function() {
        'use strict';
        return String.prototype.indexOf.apply(this, arguments) !== -1;
    };
}

回答2:

IE11 does implement String.prototype.includes so why not using the official Polyfill?

Source: polyfill source

  if (!String.prototype.includes) {
    String.prototype.includes = function(search, start) {
      if (typeof start !== 'number') {
        start = 0;
      }

      if (start + search.length > this.length) {
        return false;
      } else {
        return this.indexOf(search, start) !== -1;
      }
    };
  }

回答3:

One more solution is to use contains which will return true or false

_.contains($(".right-tree").css("background-image"), "stage1")

Hope this helps