//@param str 要复制的文本
    //@return 复制是否成功
    public webCopyString(str:string):boolean {
        let input:string = str;
        const el:any = window.document.createElement(‘textarea‘);
        el.value = input;
        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:any = window.getSelection();
        let originalRange:any = false;
        if (selection.rangeCount > 0) {
            originalRange = selection.getRangeAt(0);
        }
        window.document.body.appendChild(el);
        el.select();
        el.selectionStart = 0;
        el.selectionEnd = input.length;
        let success:boolean = false;
        try {
            success = window.document.execCommand(‘copy‘);
        }catch(err) {
            
        }
        window.document.body.removeChild(el);
        if (originalRange) {
            selection.removeAllRanges();
            selection.addRange(originalRange);
        }
        return success;
    }