如何使用Javascript在字符串中的每个新行之前/之后插入或删除选项卡？

Question

Consider the following string, as a selection in a textarea:

"I want to insert \\na tab after every newline in the this selection. \\n I also want to know how to do the opposite, removing the tab before each newline in this selection."

And a simplified example of the code involved:

var userWantsToIndentSelection = true,
userWantsToOutdentSelection = false,
start = this.selectionStart,
end = this.selectionEnd,
selection = text.slice(start,end),
newline = /\r|\n/.exec(selection);

if(newline){
    if (userWantsToIndentSelection){

        // add tabs after each newline

    }
    else if (userWantsToOutdentSelection) {

        // remove tabs before each newline

    }
}

if(!newline){

    // Handling just one line (cursor at front of line, no selection) is simple.
    // Perhaps I don't need a special handler though
    // and can use the new line handler for single and multiple line selections.
    // Mention it in your answer if you like.

}

How can I insert or remove a tab before / after every new line in a string with Javascript?

Answer 1

you can use this regex src.replace(/^/gm, "\\t");

^ matches the start of line

The m tells the regex engine to use the multi-line mode so that ^ will match each line and not only the start of the string.