<!doctype html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title> JS文本框placeholder提示</title> </head> <body> <input type="text" value="请输入关键词"> </body> <script> window.onload = function() { var defaultValue = "请输入关键词"; var input = document.getElementById("input"); input.style.color = "grey"; input.onfocus = function() { if (this.value == defaultValue) { input.value=""; setCursorPosition(this, 0); } }; input.onblur = function() { if (this.value == "") { this.value = defaultValue; } }; input.onkeypress = function(e) { e = e || window.event; var key = e.charCode || e.keyCode || e.which; if (this.value == defaultValue) { this.value = ""; this.style.color = "black"; } if (this.value.length == 1 && key == 8) { this.value = defaultValue; this.style.color = "grey"; setCursorPosition(this, 0); } }; }; function setCursorPosition(elem, index) { if (elem.setSelectionRange) { elem.focus(); elem.setSelectionRange(index, index); } else if (elem.createTextRange) { var range = elem.createTextRange(); range.collapse(true); range.moveEnd('character', index); range.moveStart('character', index); range.select(); } } </script> </html>
感兴趣的朋友可以使用在线HTML/CSS/JavaScript代码运行工具：测试一下运行效果。
更多关于JavaScript相关内容感兴趣的读者可查看本站专题：《JavaScript页面元素操作技巧总结》、《JavaScript操作DOM技巧总结》、《JavaScript切换特效与技巧总结》、《JavaScript动画特效与技巧汇总》、《JavaScript错误与调试技巧总结》、《JavaScript数据结构与算法技巧总结》及《JavaScript数学运算用法总结》