Question :
JavaScript and LocalStorage go very well, but one of them is always saying that it has no space.
The idea would be to get a solution like Gzip in JavaScript so we can compress the information to be saved in LocalStorage.
How can we do data compression in JavaScript?
Answer :
There is a very popular LZW implementation that has been redesigned to think about your current problem:
lz-string
LZ-string is designed to meet the need to store large amounts of data in localStorage, specifically on mobile devices. localStorage being generally limited to 5MB, everything you can compress is reflected in many more data that you can store.
Use
Just include the script :
<script language="javascript" src="lz-string.js"></script>
And then call the methods compress() or decompress() of object LZString() :
var string = "Isto é um teste de compressão! Recomendam-se óculos de proteção.";
alert("Tamanho da amostra é: " + string.length);
var compressed = LZString.compress(string);
alert("Tamanho da amostra após comprimida é: " + compressed.length);
string = LZString.decompress(compressed);
alert("Amostra é: " + string);
Example
We can see an example, but note that I had to include the script in the example, so the code snippet is a bit long:
var LZString={_f:String.fromCharCode,_keyStrBase64:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",_keyStrUriSafe:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-$",_getBaseValue:function(r,e){if(LZString._baseReverseDic||(LZString._baseReverseDic={}),!LZString._baseReverseDic[r]){LZString._baseReverseDic[r]={};for(var n=0;n<r.length;n++)LZString._baseReverseDic[r][r[n]]=n}return LZString._baseReverseDic[r][e]},compressToBase64:function(r){if(null==r)return"";var e=LZString._compress(r,6,function(r){return LZString._keyStrBase64.charAt(r)});switch(e.length%4){default:case 0:return e;case 1:return e+"===";case 2:return e+"==";case 3:return e+"="}},decompressFromBase64:function(r){return null==r?"":""==r?null:LZString._decompress(r.length,32,function(e){return LZString._getBaseValue(LZString._keyStrBase64,r.charAt(e))})},compressToUTF16:function(r){return null==r?"":LZString._compress(r,15,function(r){return String.fromCharCode(r+32)})+" "},decompressFromUTF16:function(r){return null==r?"":""==r?null:LZString._decompress(r.length,16384,function(e){return r.charCodeAt(e)-32})},compressToUint8Array:function(r){for(var e=LZString.compress(r),n=new Uint8Array(2*e.length),o=0,t=e.length;t>o;o++){var i=e.charCodeAt(o);n[2*o]=i>>>8,n[2*o+1]=i%256}return n},decompressFromUint8Array:function(r){if(null===r||void 0===r)return LZString.decompress(r);for(var e=new Array(r.length/2),n=0,o=e.length;o>n;n++)e[n]=256*r[2*n]+r[2*n+1];var t=[];return e.forEach(function(r){t.push(String.fromCharCode(r))}),LZString.decompress(t.join(""))},compressToEncodedURIComponent:function(r){return null==r?"":LZString._compress(r,6,function(r){return LZString._keyStrUriSafe.charAt(r)})},decompressFromEncodedURIComponent:function(r){return null==r?"":""==r?null:(r=r.replace(/ /g,"+"),LZString._decompress(r.length,32,function(e){return LZString._getBaseValue(LZString._keyStrUriSafe,r.charAt(e))}))},compress:function(r){return LZString._compress(r,16,function(r){return String.fromCharCode(r)})},_compress:function(r,e,n){if(null==r)return"";{var o,t,i,s={},a={},p="",u="",c="",l=2,f=3,h=2,g=[],d=0,S=0;LZString._f}for(i=0;i<r.length;i+=1)if(p=r[i],Object.prototype.hasOwnProperty.call(s,p)||(s[p]=f++,a[p]=!0),u=c+p,Object.prototype.hasOwnProperty.call(s,u))c=u;else{if(Object.prototype.hasOwnProperty.call(a,c)){if(c.charCodeAt(0)<256){for(o=0;h>o;o++)d<<=1,S==e-1?(S=0,g.push(n(d)),d=0):S++;for(t=c.charCodeAt(0),o=0;8>o;o++)d=d<<1|1&t,S==e-1?(S=0,g.push(n(d)),d=0):S++,t>>=1}else{for(t=1,o=0;h>o;o++)d=d<<1|t,S==e-1?(S=0,g.push(n(d)),d=0):S++,t=0;for(t=c.charCodeAt(0),o=0;16>o;o++)d=d<<1|1&t,S==e-1?(S=0,g.push(n(d)),d=0):S++,t>>=1}l--,0==l&&(l=Math.pow(2,h),h++),delete a[c]}else for(t=s[c],o=0;h>o;o++)d=d<<1|1&t,S==e-1?(S=0,g.push(n(d)),d=0):S++,t>>=1;l--,0==l&&(l=Math.pow(2,h),h++),s[u]=f++,c=String(p)}if(""!==c){if(Object.prototype.hasOwnProperty.call(a,c)){if(c.charCodeAt(0