为什么这个文本区域似乎只添加一个空格而不是四个空格? [英] Why does this textarea appear to only add one space instead of four?

问题描述

这是我的代码:

doc.on("keydown", ".textarea_code_snippet", function(e) {
    if(e.keyCode === 9) { // tab was pressed

        // get caret position/selection
        var start = this.selectionStart;
        var end = this.selectionEnd;

        var $this = $(this);
        var value = $this.val();

        // set textarea value to: text before caret + tab + text
        // after caret 
        $this.val(value.substring(0, start)
                    + "\t"
                    + value.substring(end));

        // put caret at right position again (add one for the tab)
        this.selectionStart = this.selectionEnd = start + 1;

        // prevent the focus lose
        e.preventDefault();
    }
});

它处理<textarea>中的 Tab 密钥.当您按下 Tab 键时，会将\t附加到文本区域.现在，我想添加4个空格.这是我的新版本:

It handles Tab key in the <textarea>. It appends \t to the textarea when you press the Tab key. Now I want to add 4 spaces instead. Here is my new version:

.
.
 $this.val(value.substring(0, start)
             + "    "
             + value.substring(end));
.
.

但是当我按 Tab 时，它仅将一个空间附加到文本区域.我该如何解决?

But it appends only one space to the textarea when I press Tab. How can I fix it?

推荐答案

确实添加四个空格.您只是忘了调整一件事:

It does add four spaces. You just forgot to adjust one thing:

// put caret at right position again (add one for the tab)
this.selectionStart = this.selectionEnd = start + 1;

您可能会看到插入符号仅移动了一个空格.您需要将以上行更改为:

You probably see the caret move by only one space. You need to change the above lines to:

// Put caret at right position again (add four for four spaces)
this.selectionStart = this.selectionEnd = start + 4;

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