Alexander Solonik Alexander Solonik - 4 months ago 16
Javascript Question

Understanding HTML string escaping in javascript

Hey i was just going though this plugin code online HERE:

$("#filer_input2").filer({
limit: null,
maxSize: null,
extensions: null,
changeInput: '<div class="jFiler-input-dragDrop"><div class="jFiler-input-inner"><div class="jFiler-input-icon"><i class="icon-jfi-cloud-up-o"></i></div><div class="jFiler-input-text"><h3>Drag&Drop files here</h3> <span style="display:inline-block; margin: 15px 0">or</span></div><a class="jFiler-input-choose-btn blue">Browse Files</a></div></div>',
showThumbs: true,
theme: "dragdropbox",
templates: {
box: '<ul class="jFiler-items-list jFiler-items-grid"></ul>',
item: '<li class="jFiler-item">\
<div class="jFiler-item-container">\
<div class="jFiler-item-inner">\
<div class="jFiler-item-thumb">\
<div class="jFiler-item-status"></div>\
<div class="jFiler-item-info">\
<span class="jFiler-item-title"><b title="{{fi-name}}">{{fi-name | limitTo: 25}}</b></span>\
<span class="jFiler-item-others">{{fi-size2}}</span>\
</div>\
{{fi-image}}\
</div>\
<div class="jFiler-item-assets jFiler-row">\
<ul class="list-inline pull-left">\
<li>{{fi-progressBar}}</li>\
</ul>\
<ul class="list-inline pull-right">\
<li><a class="icon-jfi-trash jFiler-item-trash-action"></a></li>\
</ul>\
</div>\
</div>\
</div>\
</li>',
itemAppend: '<li class="jFiler-item">\
<div class="jFiler-item-container">\
<div class="jFiler-item-inner">\
<div class="jFiler-item-thumb">\
<div class="jFiler-item-status"></div>\
<div class="jFiler-item-info">\
<span class="jFiler-item-title"><b title="{{fi-name}}">{{fi-name | limitTo: 25}}</b></span>\
<span class="jFiler-item-others">{{fi-size2}}</span>\
</div>\
{{fi-image}}\
</div>\
<div class="jFiler-item-assets jFiler-row">\
<ul class="list-inline pull-left">\
<li><span class="jFiler-item-others">{{fi-icon}}</span></li>\
</ul>\
<ul class="list-inline pull-right">\
<li><a class="icon-jfi-trash jFiler-item-trash-action"></a></li>\
</ul>\
</div>\
</div>\
</div>\
</li>',
progressBar: '<div class="bar"></div>',
itemAppendToEnd: false,
removeConfirmation: true,
_selectors: {
list: '.jFiler-items-list',
item: '.jFiler-item',
progressBar: '.bar',
remove: '.jFiler-item-trash-action'
}
},
dragDrop: {
dragEnter: null,
dragLeave: null,
drop: null,
},
uploadFile: {
url: "./php/upload.php",
data: null,
type: 'POST',
enctype: 'multipart/form-data',
beforeSend: function(){},
success: function(data, el){
var parent = el.find(".jFiler-jProgressBar").parent();
el.find(".jFiler-jProgressBar").fadeOut("slow", function(){
$("<div class=\"jFiler-item-others text-success\"><i class=\"icon-jfi-check-circle\"></i> Success</div>").hide().appendTo(parent).fadeIn("slow");
});
},
error: function(el){
var parent = el.find(".jFiler-jProgressBar").parent();
el.find(".jFiler-jProgressBar").fadeOut("slow", function(){
$("<div class=\"jFiler-item-others text-error\"><i class=\"icon-jfi-minus-circle\"></i> Error</div>").hide().appendTo(parent).fadeIn("slow");
});
},
statusCode: null,
onProgress: null,
onComplete: null
},
files: null,
addMore: false,
clipBoardPaste: true,
excludeName: null,
beforeRender: null,
afterRender: null,
beforeShow: null,
beforeSelect: null,
onSelect: null,
afterShow: null,
onRemove: function(itemEl, file, id, listEl, boxEl, newInputEl, inputEl){
var file = file.name;
$.post('./php/remove_file.php', {file: file});
},
onEmpty: null,
options: null,
captions: {
button: "Choose Files",
feedback: "Choose files To Upload",
feedback2: "files were chosen",
drop: "Drop file here to Upload",
removeConfirmation: "Are you sure you want to remove this file?",
errors: {
filesLimit: "Only {{fi-limit}} files are allowed to be uploaded.",
filesType: "Only Images are allowed to be uploaded.",
filesSize: "{{fi-name}} is too large! Please upload file up to {{fi-maxSize}} MB.",
filesSizeAll: "Files you've choosed are too large! Please upload files up to {{fi-maxSize}} MB."
}
}
});


I know that the above is quite a wall of code , so let me narrow down on my difficulty:

itemAppend: '<li class="jFiler-item">\
<div class="jFiler-item-container">\
<div class="jFiler-item-inner">\
<div class="jFiler-item-thumb">\
<div class="jFiler-item-status"></div>\
<div class="jFiler-item-info">\
<span class="jFiler-item-title"><b title="{{fi-name}}">{{fi-name | limitTo: 25}}</b></span>\
<span class="jFiler-item-others">{{fi-size2}}</span>\
</div>\
{{fi-image}}\
</div>\
<div class="jFiler-item-assets jFiler-row">\
<ul class="list-inline pull-left">\
<li><span class="jFiler-item-others">{{fi-icon}}</span></li>\
</ul>\
<ul class="list-inline pull-right">\
<li><a class="icon-jfi-trash jFiler-item-trash-action"></a></li>\
</ul>\
</div>\
</div>\
</div>\
</li>',


why are all those escape characters doing at the end of the html elements I.E the
\
??? can somebody explain ?

Thanks.

Answer

Normal JavaScript string literals cannot have unescaped newlines in them:

// Syntax error
var str = "This is
a test";

With the backslash escaping the newline, you can have a line break without using a close quote and +:

// Escaping the newline makes it valid
var str = "This is\
a test";

The newline will not be in the string (but all the leading whitespace at the beginning of the next line will be).

Example:

var str =
    "this is\
    a test";
console.log(JSON.stringify(str));

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