JavaScript get word before cursor

问题:

Okay, I've been looking all over the web to find a solution but I couldn't find one, is there a way to get the word before the caret position in an editable div so a bit like:

This is some| demo texts

This should return the word "some"... I don't know if this is possible, I would be glad for any help, thanks :).

回答1:

With using Caret Position finder method provided here this will do what you want.

function ReturnWord(text, caretPos) {
    var index = text.indexOf(caretPos);
    var preText = text.substring(0, caretPos);
    if (preText.indexOf(" ") > 0) {
        var words = preText.split(" ");
        return words[words.length - 1]; //return last word
    }
    else {
        return preText;
    }
}

function AlertPrevWord() {
    var text = document.getElementById("textArea");
    var caretPos = GetCaretPosition(text)
    var word = ReturnWord(text.value, caretPos);
    if (word != null) {
        alert(word);
    }

}

function GetCaretPosition(ctrl) {
    var CaretPos = 0;   // IE Support
    if (document.selection) {
        ctrl.focus();
        var Sel = document.selection.createRange();
        Sel.moveStart('character', -ctrl.value.length);
        CaretPos = Sel.text.length;
    }
    // Firefox support
    else if (ctrl.selectionStart || ctrl.selectionStart == '0')
        CaretPos = ctrl.selectionStart;
    return (CaretPos);
}

<input id="textArea" type="text" />
<br />
<input id="Submit" type="submit" value="Test" onclick="AlertPrevWord()" />

Here is also a jsfiddle.

回答2:

Here is a rough method using the Selection and Range objects.

function getWord() {
    var range = window.getSelection().getRangeAt(0);
    if (range.collapsed) {
        text = range.startContainer.textContent.substring(0, range.startOffset+1);
        return text.split(/\b/g).pop();
    }
    return '';
}

You can see it in action here: http://jsfiddle.net/ggfFw/1/. This will not work in IE. If you need IE support look at the Rangy library.

回答3:

I had something like that https://stackoverflow.com/a/9960262/986160 yet at some point it wasn't getting a selection in my Chrome browser. Based on my other answer here: https://stackoverflow.com/a/26728677/986160 - I changed it accordingly to be:

function getLastWordBeforeCaret() {
    const containerEl = document.getElementById('element-id');
    let preceding = '';
    let sel;
    let range;
    if (window.getSelection) {
        sel = window.getSelection();
        if (sel && sel.rangeCount > 0) {
            range = sel.getRangeAt(0).cloneRange();
            range.collapse(true);
            range.setStart(containerEl, 0);
            preceding = range.toString();
        }
    }
    let queryMatch = preceding.match(/([^\s]+)$/i);
    if (queryMatch) {
        return queryMatch[1];
    } else {
        return '';
    }
}