onkeyup char position in string
How does one find the position of the character being entered into the string on keypress using JavaScript? I am trying to build an input mask and the user should not be allowed to input mor开发者_开发知识库e than 13 characters.
I think the answer to your direct question is that the selectionStart attribute of the input field will tell you where the insertion cursor is.
function myKeypress() {
console.log(this.selectionStart); // tells you where the insertion cursor is
}
By also looking at selectionEnd you can see if one or more characters are selected too rather than just a plain insertion point.
somethink like this may work:
<html>
<body>
<form>
<input type="text" name='element1' maxlength="13" />
</form>
</body>
</html>
Try this code in your browser --- should give you the tools to accomplish your task.
<html>
<body>
<script type="text/javascript">
function getTextAreaSelection() {
var textArea = document.getElementById('textarea1');
if (document.selection) { //IE
var bm = document.selection.createRange().getBookmark();
var sel = textArea.createTextRange();
sel.moveToBookmark(bm);
var sleft = textArea.createTextRange();
sleft.collapse(true);
sleft.setEndPoint("EndToStart", sel);
textArea.selectionStart = sleft.text.length
textArea.selectionEnd = sleft.text.length + sel.text.length;
textArea.selectedText = sel.text;
}
else if (textArea.selectionStart){ //FF
textArea.selectedText = textArea.value.substring(textArea.selectionStart,textArea.selectionEnd);
}
alert("Selection Start==> " + textArea.selectionStart + "\n" +
"Selection End ==> " + textArea.selectionEnd + "\n" +
"Selected Text ==> " + textArea.selectedText + "\n" +
"TextArea Value ==> " + textArea.value);
}
</script>
<form>
<textarea id="textarea1">Hello world</textarea>
<input type="button" onClick="getTextAreaSelection();return false;" value="Get Selection"/>
</form>
</body>
</html>
加载中,请稍侯......
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