H5編輯器核心思想的實(shí)例分析

var range = getRangeObject();var start = range.startOffset,
end = range.endOffset;var startContainer = range.startContainer;var endContainer = range.endContainer;

function getRangeObject(){if(window.getSelection)
{var selection = window.getSelection();if(selection.rangeCount > 0)
{return selection.getRangeAt(0);
}
}else if(document.selection)
{return document.selection.createRange(); 
}return null;
};

function getNextTextNode(startNode,dir = "nextSibling"){//記錄startNode變化之前的狀態(tài)，startNode變化后無效時便于狀態(tài)的回滾let unchangeNode = startNode;if(startNode.nodeType == 3){
 startNode = startNode[dir];
 }while (true){if(startNode == undefined){if(unchangeNode == undefined){//保護(hù)機(jī)制throw new Error("程序會陷入死循環(huán)");break;
  }/*startNode所在的父元素所有選中節(jié)點(diǎn)遍歷完畢，將sartNode指向父元素的兄弟節(jié)點(diǎn)*/let parent = unchangeNode.parentElement;
  unchangeNode = parent;
  startNode = parent[dir];
 }else if(startNode.nodeType == 3){//文本節(jié)點(diǎn)則退出循環(huán)break;
 }else if(startNode.tagName == "BR"){//處理單標(biāo)簽,避免不必要的迭代unchangeNode = startNode;
  startNode = startNode[dir];
 }else if(startNode.nodeType == 1){/*如果是雙標(biāo)簽元素則進(jìn)入*/unchangeNode = startNode;if(dir == "previousSibling"){

  startNode = $(startNode).contents().last().get(0);
  }else if(dir == "nextSibling"){
  startNode = $(startNode).contents().first().get(0);
  }else {//便于錯誤的定位throw new Error("錯誤的遍歷方向:"+dir);
  }
 }else {//便于錯誤的定位throw new Error("不期待的元素類型=》"+startNode);

 }
 } return startNode;
 
}

function getTextNodes(startTextNode,endTextNode){
 let textNodeArray = [];
 let node = startTextNode;while (true) {
 node = getNextTextNode(node);if(node == endTextNode){break;
 }
 textNodeArray.push(node);
 } return textNodeArray;
}