建一个ts文件，js文件不行，复制下面的代码，在场景中给button绑定事件

// Learn TypeScript:
//  - https://docs.cocos.com/creator/manual/en/scripting/typescript.html
// Learn Attribute:
//  - https://docs.cocos.com/creator/manual/en/scripting/reference/attributes.html
// Learn life-cycle callbacks:
//  - https://docs.cocos.com/creator/manual/en/scripting/life-cycle-callbacks.html

const {ccclass, property} = cc._decorator;

@ccclass
export default class CopyText extends cc.Component {

    @property(cc.Label)
    _textDisplayArea: cc.Label = null;

    start () {
        this._textDisplayArea = cc.find("Canvas/文字展示区/ScrollView/view/content/item").getComponent(cc.Label);
    }
      //拷贝文本
      CopyTextEvent () {
        let input = this._textDisplayArea.string;

        const el = document.createElement('textarea');

        el.value = input;

        // Prevent keyboard from showing on mobile
        el.setAttribute('readonly', '');

        el.style.contain = 'strict';
        el.style.position = 'absolute';
        el.style.left = '-9999px';
        el.style.fontSize = '12pt'; // Prevent zooming on iOS

        const selection = getSelection();
        let originalRange;
        if (selection.rangeCount > 0) {
            originalRange = selection.getRangeAt(0);
        }

        document.body.appendChild(el);
        el.select();

        // Explicit selection workaround for iOS
        el.selectionStart = 0;
        el.selectionEnd = input.length;

        let success = false;
        try {
            success = document.execCommand('copy');
        } catch (err) {}

        document.body.removeChild(el);

        if (originalRange) {
            selection.removeAllRanges();
            selection.addRange(originalRange);
        }


        console.log("拷贝文本");
    }
}