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June 18, 2017 11:07
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| <!doctype html> | |
| <textarea id="input"></textarea> | |
| <script> | |
| input.onkeydown = function(eve){ | |
| if(eve.keyCode === 13){ | |
| eve.preventDefault() | |
| var str = this.value | |
| var ss = this.selectionStart | |
| var se = this.selectionEnd | |
| var ls = seekPreLineBeginning(str, ss) | |
| var match = str.slice(ls, ss).match(/^[ \t]*/) | |
| var ins = match && !eve.shiftKey | |
| ? "\n" + match[0] | |
| : "\n" | |
| this.value = insertString(removeString(str, ss, se - ss), ss, ins) | |
| this.selectionStart = this.selectionEnd = ss + ins.length | |
| }else if(eve.keyCode === 9){ | |
| eve.preventDefault() | |
| var str = this.value | |
| var ss = this.selectionStart | |
| var se = this.selectionEnd | |
| var ls = seekPreLineBeginning(str, ss) | |
| if(eve.shiftKey){ | |
| if(str[ls].match(/\s/)){ | |
| this.value = removeString(str, ls, 1) | |
| this.selectionStart = Math.max(ls, ss - 1) | |
| this.selectionEnd = Math.max(ls, se - 1) | |
| } | |
| }else{ | |
| this.value = insertString(str, ls, "\t") | |
| this.selectionEnd = se + 1 | |
| this.selectionStart = ss + 1 | |
| } | |
| } | |
| } | |
| function seekPreLineBeginning(str, pos){ | |
| while(--pos >= 0 && str[pos] !== "\n"){} | |
| return pos + 1 | |
| } | |
| function insertString(base_str, pos, add_str){ | |
| return base_str.substr(0, pos) + add_str + base_str.substr(pos) | |
| } | |
| function removeString(base_str, pos, len){ | |
| return base_str.substr(0, pos) + base_str.substr(pos + len) | |
| } | |
| </script> |
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