在微信浏览器中使用JavaScript实现文本复制功能

// 检测是否iOS端
function iosAgent() {
    return navigator.userAgent.match(/(iPhone|iPod|iPad);?/i);
}

// 复制文本函数，微信端，需要在用户触发 Click 事件里面才能执行成功
function copy(message) {
    if (iosAgent()) {
        console.log("input 复制方式 " + message);
        let inputObj = document.createElement("input");
        inputObj.value = message;
        document.body.appendChild(inputObj);
        inputObj.select();
        inputObj.setSelectionRange(0, inputObj.value.length);
        _execCommand('Copy');
        document.body.removeChild(inputObj);
    } else {
        console.log("document 复制方式 " + message);
        let domObj = document.createElement("span");
        domObj.innerHTML = message;
        document.body.appendChild(domObj);
        let selection = window.getSelection();
        let range = document.createRange();
        range.selectNodeContents(domObj);
        selection.removeAllRanges();
        selection.addRange(range);
        _execCommand('Copy');
        document.body.removeChild(domObj);
    }
}

// 执行浏览器命令 Copy 顺便输出一下日志，如果在移动端推荐写个方法展示日志或者用alert(msg)也行。
function _execCommand(action) {
    let is = document.execCommand(action);
    if (is) {
        console.log("复制成功");
    } else {
        console.log("复制失败");
    }
}

<button id="copyButton">复制文本</button>

<script>
document.getElementById("copyButton").addEventListener("click", function() {
    var textToCopy = "要复制的文本内容";
    copy(textToCopy);
});
</script>