Just use the entity code 

for a linebreak in a title attribute.
<a title="First Line 
Second Line">Hover Me </a>
it is possible to add linebreaks within native HTML tooltips by simply having the title attribute spread over mutliple lines.
However, I'd recommend using a jQuery tooltip plugin such as Q-Tip: http://craigsworks.com/projects/qtip/.
It is simple to set up and use. Alternatively there are a lot of free javascript tooltip plugins around too.
edit: correction on first statement.
AngularJS with Bootstrap UI Tolltip (uib-tooltip), has three versions of tool-tip:
uib-tooltip, uib-tooltip-template and uib-tooltip-html
- uib-tooltip takes only text and will escape any HTML provided
- uib-tooltip-html takes an expression that evaluates to an HTML string
- uib-tooltip-template takes a text that specifies the location of the template
In my case, I opted for uib-tooltip-html and there are three parts to it:
Example:
(function(angular) {
//Step 1: configure $sceProvider - this allows the configuration of $sce service.
angular.module('myApp', ['uib.bootstrap'])
.config(function($sceProvider) {
$sceProvider.enabled(false);
});
//Step 2: Set the tooltip content in the controller
angular.module('myApp')
.controller('myController', myController);
myController.$inject = ['$sce'];
function myController($sce) {
var vm = this;
vm.tooltipContent = $sce.trustAsHtml('I am the first line <br /><br />' +
'I am the second line-break');
return vm;
}
})(window.angular);
//Step 3: Use the tooltip in HTML (UI)
<div ng-controller="myController as get">
<span uib-tooltip-html="get.tooltipContent">other Contents</span>
</div>
For more information, please check here
This CSS is what finally worked for me in conjunction with a linefeed in my editor:
.tooltip-inner {
white-space: pre-wrap;
}
Found here: How to make Twitter bootstrap tooltips have multiple lines?
Use

There shouldn't be any ; character.
Hi this code will work in all browser !!i used for new line in chrome and safari and ul li for IE
function genarateMultiLIneCode(){
var =values["a","b","c"];
const liStart = '<li>';
const liEnd = '</li>';
const bullet = '• ';
var mergedString = ' ';
const unOrderListStart='<ul>'
const unOrderListEnd='</ul>'
const fakeNewline = '
';
for (let i = 0; i < values.length; i++) {
mergedString += liStart + bullet + values[i] + liEnd + fakeNewline;
}
const tempElement = document.createElement("div");
tempElement.innerHTML = unOrderListStart + mergedString + unOrderListEnd;
return tempElement.innerText;
}
}