JavaScript让Textarea支持tab按键的方法
本文实例讲述了JavaScript让Textarea支持tab按键的方法。分享给大家供大家参考。具体实现方法如下:
HTMLTextAreaElement.prototype.getCaretPosition = function () {
//return the caret position of the textarea
return this.selectionStart;
};
HTMLTextAreaElement.prototype.setCaretPosition = function (position) {
//change the caret position of the textarea
this.selectionStart = position;
this.selectionEnd = position;
this.focus();
};
HTMLTextAreaElement.prototype.hasSelection = function () {
//if the textarea has selection then return true
if (this.selectionStart == this.selectionEnd) {
return false;
} else {
return true;
}
};
HTMLTextAreaElement.prototype.getSelectedText = function () {
//return the selection text
return this.value.substring(this.selectionStart, this.selectionEnd);
};
HTMLTextAreaElement.prototype.setSelection = function (start, end) {
//change the selection area of the textarea
this.selectionStart = start;
this.selectionEnd = end;
this.focus();
};
var textarea = document.getElementsByTagName('textarea')[0];
textarea.onkeydown = function(event) {
//support tab on textarea
if (event.keyCode == 9) { //tab was pressed
var newCaretPosition;
newCaretPosition = textarea.getCaretPosition() + " ".length;
textarea.value = textarea.value.substring(0, textarea.getCaretPosition()) + " " + textarea.value.substring(textarea.getCaretPosition(), textarea.value.length);
textarea.setCaretPosition(newCaretPosition);
return false;
}
if(event.keyCode == 8){
//backspace
if (textarea.value.substring(textarea.getCaretPosition() - 4, textarea.getCaretPosition()) == " ") {
//it's a tab space
var newCaretPosition;
newCaretPosition = textarea.getCaretPosition() - 3;
textarea.value = textarea.value.substring(0, textarea.getCaretPosition() - 3) + textarea.value.substring(textarea.getCaretPosition(), textarea.value.length);
textarea.setCaretPosition(newCaretPosition);
}
}
if(event.keyCode == 37){ //left arrow
var newCaretPosition;
if (textarea.value.substring(textarea.getCaretPosition() - 4, textarea.getCaretPosition()) == " ") {
//it's a tab space
newCaretPosition = textarea.getCaretPosition() - 3;
textarea.setCaretPosition(newCaretPosition);
}
}
if(event.keyCode == 39){
//right arrow
var newCaretPosition;
if (textarea.value.substring(textarea.getCaretPosition() + 4, textarea.getCaretPosition()) == " ") {
//it's a tab space
newCaretPosition = textarea.getCaretPosition() + 3;
textarea.setCaretPosition(newCaretPosition);
}
}
}
希望本文所述对大家的javascript程序设计有所帮助。
热文精选
更多资讯推荐
更多- Stable Diffusion 2.0 发布,加强成人内容过滤
- .NET 7 正式发布
- A3Mall 开源商城系统 v2.1 发布
- FydeOS v14 版本更新:优化输入法体验+重构安卓子系统+全新应用启动器
- ThinkPHP V6.0.8版本发布——多环境变量配置支持
- 毕昇 JDK 8u292、11.0.11 发布!
- KubeVela 1.0:开启可编程式应用平台的未来
- Eclipse 4.19 稳定版发布
- 阿里巴巴 Arthas 3.5.0 版本发布,支持反编译打印行号和统一鉴权
- Debian 11 Bullseye 即将进入冻结,Debian 13 代号 Trixie
- Rancher 2.5 发布,新增支持边缘集群的 GitOps
- FlashDB IoT 超轻量级嵌入式数据库