如何获取输入字段左侧的文本

<label for="inputField">左侧文本</label>
<input type="text" id="inputField">

<style>
    .inputField {
        background-image: url('left-text.png');
        background-position: left center;
        background-repeat: no-repeat;
        padding-left: 20px; /* 根据左侧文本的宽度调整 */
    }
</style>

<input type="text" class="inputField">

<script>
    function getLeftText() {
        var inputField = document.getElementById("inputField");
        var leftText = inputField.previousSibling.textContent.trim();
        alert(leftText);
    }
</script>

<span>左侧文本</span>
<input type="text" id="inputField">
<button onclick="getLeftText()">获取左侧文本</button>