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Three AngularJS directives that can improve the user experience

  • 2020-06-15 07:49:09
  • OfStack

1. Profile picture

To display avatar images in your app, you need to use the user's email address, convert the address to lowercase and encrypt the string using md5. So the smart thing to do is to use instructions to do this, and reuse them. 


 
/*
 * A simple Gravatar Directive
 * @example
 *  <gravatar-image email="test@email.com" size="50"></gravatar-image>
 */
app.directive('gravatarImage', function () {
 return {
  restrict: 'AE',
  replace: true,
  required: 'email',
  template: '<img ng-src="https://www.gravatar.com/avatar/{{hash}}?s={{size}}&d=identicon" />',
  link: function (scope, element, attrs) {
   attrs.$observe('email', function (value) {
    if(!value) { return; }
 
    // MD5 (Message-Digest Algorithm) by WebToolkit
    var md5=function(s){function L(k,d){return(k<<d)|(k>>>(32-d));}function K(G,k){var I,d,F,H,x;F=(G&2147483648);H=(k&2147483648);I=(G&1073741824);d=(k&1073741824);x=(G&1073741823)+(k&1073741823);if(I&d){return(x^2147483648^F^H);}if(I|d){if(x&1073741824){return(x^3221225472^F^H);}else{return(x^1073741824^F^H);}}else{return(x^F^H);}}function r(d,F,k){return(d&F)|((~d)&k);}function q(d,F,k){return(d&k)|(F&(~k));}function p(d,F,k){return(d^F^k);}function n(d,F,k){return(F^(d|(~k)));}function u(G,F,aa,Z,k,H,I){G=K(G,K(K(r(F,aa,Z),k),I));return K(L(G,H),F);}function f(G,F,aa,Z,k,H,I){G=K(G,K(K(q(F,aa,Z),k),I));return K(L(G,H),F);}function D(G,F,aa,Z,k,H,I){G=K(G,K(K(p(F,aa,Z),k),I));return K(L(G,H),F);}function t(G,F,aa,Z,k,H,I){G=K(G,K(K(n(F,aa,Z),k),I));return K(L(G,H),F);}function e(G){var Z;var F=G.length;var x=F+8;var k=(x-(x%64))/64;var I=(k+1)*16;var aa=Array(I-1);var d=0;var H=0;while(H<F){Z=(H-(H%4))/4;d=(H%4)*8;aa[Z]=(aa[Z]|(G.charCodeAt(H)<<d));H++;}Z=(H-(H%4))/4;d=(H%4)*8;aa[Z]=aa[Z]|(128<<d);aa[I-2]=F<<3;aa[I-1]=F>>>29;return aa;}function B(x){var k="",F="",G,d;for(d=0;d<=3;d++){G=(x>>>(d*8))&255;F="0"+G.toString(16);k=k+F.substr(F.length-2,2);}return k;}function J(k){k=k.replace(/rn/g,"n");var d="";for(var F=0;F<k.length;F++){var x=k.charCodeAt(F);if(x<128){d+=String.fromCharCode(x);}else{if((x>127)&&(x<2048)){d+=String.fromCharCode((x>>6)|192);d+=String.fromCharCode((x&63)|128);}else{d+=String.fromCharCode((x>>12)|224);d+=String.fromCharCode(((x>>6)&63)|128);d+=String.fromCharCode((x&63)|128);}}}return d;}var C=Array();var P,h,E,v,g,Y,X,W,V;var S=7,Q=12,N=17,M=22;var A=5,z=9,y=14,w=20;var o=4,m=11,l=16,j=23;var U=6,T=10,R=15,O=21;s=J(s);C=e(s);Y=1732584193;X=4023233417;W=2562383102;V=271733878;for(P=0;P<C.length;P+=16){h=Y;E=X;v=W;g=V;Y=u(Y,X,W,V,C[P+0],S,3614090360);V=u(V,Y,X,W,C[P+1],Q,3905402710);W=u(W,V,Y,X,C[P+2],N,606105819);X=u(X,W,V,Y,C[P+3],M,3250441966);Y=u(Y,X,W,V,C[P+4],S,4118548399);V=u(V,Y,X,W,C[P+5],Q,1200080426);W=u(W,V,Y,X,C[P+6],N,2821735955);X=u(X,W,V,Y,C[P+7],M,4249261313);Y=u(Y,X,W,V,C[P+8],S,1770035416);V=u(V,Y,X,W,C[P+9],Q,2336552879);W=u(W,V,Y,X,C[P+10],N,4294925233);X=u(X,W,V,Y,C[P+11],M,2304563134);Y=u(Y,X,W,V,C[P+12],S,1804603682);V=u(V,Y,X,W,C[P+13],Q,4254626195);W=u(W,V,Y,X,C[P+14],N,2792965006);X=u(X,W,V,Y,C[P+15],M,1236535329);Y=f(Y,X,W,V,C[P+1],A,4129170786);V=f(V,Y,X,W,C[P+6],z,3225465664);W=f(W,V,Y,X,C[P+11],y,643717713);X=f(X,W,V,Y,C[P+0],w,3921069994);Y=f(Y,X,W,V,C[P+5],A,3593408605);V=f(V,Y,X,W,C[P+10],z,38016083);W=f(W,V,Y,X,C[P+15],y,3634488961);X=f(X,W,V,Y,C[P+4],w,3889429448);Y=f(Y,X,W,V,C[P+9],A,568446438);V=f(V,Y,X,W,C[P+14],z,3275163606);W=f(W,V,Y,X,C[P+3],y,4107603335);X=f(X,W,V,Y,C[P+8],w,1163531501);Y=f(Y,X,W,V,C[P+13],A,2850285829);V=f(V,Y,X,W,C[P+2],z,4243563512);W=f(W,V,Y,X,C[P+7],y,1735328473);X=f(X,W,V,Y,C[P+12],w,2368359562);Y=D(Y,X,W,V,C[P+5],o,4294588738);V=D(V,Y,X,W,C[P+8],m,2272392833);W=D(W,V,Y,X,C[P+11],l,1839030562);X=D(X,W,V,Y,C[P+14],j,4259657740);Y=D(Y,X,W,V,C[P+1],o,2763975236);V=D(V,Y,X,W,C[P+4],m,1272893353);W=D(W,V,Y,X,C[P+7],l,4139469664);X=D(X,W,V,Y,C[P+10],j,3200236656);Y=D(Y,X,W,V,C[P+13],o,681279174);V=D(V,Y,X,W,C[P+0],m,3936430074);W=D(W,V,Y,X,C[P+3],l,3572445317);X=D(X,W,V,Y,C[P+6],j,76029189);Y=D(Y,X,W,V,C[P+9],o,3654602809);V=D(V,Y,X,W,C[P+12],m,3873151461);W=D(W,V,Y,X,C[P+15],l,530742520);X=D(X,W,V,Y,C[P+2],j,3299628645);Y=t(Y,X,W,V,C[P+0],U,4096336452);V=t(V,Y,X,W,C[P+7],T,1126891415);W=t(W,V,Y,X,C[P+14],R,2878612391);X=t(X,W,V,Y,C[P+5],O,4237533241);Y=t(Y,X,W,V,C[P+12],U,1700485571);V=t(V,Y,X,W,C[P+3],T,2399980690);W=t(W,V,Y,X,C[P+10],R,4293915773);X=t(X,W,V,Y,C[P+1],O,2240044497);Y=t(Y,X,W,V,C[P+8],U,1873313359);V=t(V,Y,X,W,C[P+15],T,4264355552);W=t(W,V,Y,X,C[P+6],R,2734768916);X=t(X,W,V,Y,C[P+13],O,1309151649);Y=t(Y,X,W,V,C[P+4],U,4149444226);V=t(V,Y,X,W,C[P+11],T,3174756917);W=t(W,V,Y,X,C[P+2],R,718787259);X=t(X,W,V,Y,C[P+9],O,3951481745);Y=K(Y,h);X=K(X,E);W=K(W,v);V=K(V,g);}var i=B(Y)+B(X)+B(W)+B(V);return i.toLowerCase();};
 
    scope.hash = md5(value.toLowerCase());
    scope.size = attrs.size;
 
    if(angular.isUndefined(scope.size)) {
     scope.size = 60; // default to 60 pixels
    }
   });
  }
 };
});

2. Pay attention to me

This is actually a very short instruction, but it's great. In the following example, the user clicks on a link and the input box needs to be automatically focused. This way, the user does not have to manually click the text field when the page is displayed. 


/**
 * Sets focus to this element if the value of focus-me is true.
 * @example
 * <a ng-click="addName=true">add name</a>
 * <input ng-show="addName" type="text" ng-model="name" focus-me="{{addName}}" />
 */
app.directive('focusMe', ['$timeout', function($timeout) {
 return {
  scope: { trigger: '@focusMe' },
  link: function(scope, element) {
   scope.$watch('trigger', function(value) {
    if(value === "true") {
     $timeout(function() {
      element[0].focus();
     });
    }
   });
  }
 };
}]);

3.Contenteditable element model binding

The main reason we use contenteditable instead of textarea elements is that there are no restrictions on layout and UI. Using this directive in the editor, we can achieve a two-way binding between html and ES22en-ES23en of the contenteditable element. Currently, ES25en-ES26en is not supported in the contenteditable element. 


/**
 * Two-way data binding for contenteditable elements with ng-model.
 * @example
 *  <p contenteditable="true" ng-model="text"></p>
 */
app.directive('contenteditable', function() {
 return {
  require: '?ngModel',
  link: function(scope, element, attrs, ctrl) {
 
   // Do nothing if this is not bound to a model
   if (!ctrl) { return; }
 
   // Checks for updates (input or pressing ENTER)
   // view -> model
   element.bind('input enterKey', function() {
    var rerender = false;
    var html = element.html();
 
    if (attrs.noLineBreaks) {
     html = html.replace(/<div>/g, '').replace(/<br>/g, '').replace(/<\/div>/g, '');
     rerender = true;
    }
 
    scope.$apply(function() {
     ctrl.$setViewValue(html);
     if(rerender) {
      ctrl.$render();
     }
    });
   });
 
   element.keyup(function(e){
    if(e.keyCode === 13){
     element.trigger('enterKey');
    }
   });
 
   // model -> view
   ctrl.$render = function() {
    element.html(ctrl.$viewValue);
   };
 
   // load init value from DOM
   ctrl.$render();
  }
 };
});

Conclusion: THE AngularJS directive can be used to improve the user experience

I hope that the introduction of the AngularJS directive gives you some insight into its usefulness.

To me, directives are the most exciting feature of AngularJS. Creating reusable components that can be added to a pure HTML application library is incredibly powerful. Because instructions are practical, and most of them are easy to write, many developers have already developed many instructions for popular libraries. For example, the AngularJS team has created a series 1 directive for Bootstrap (does anyone not use it?). Is called UI Bootstrap.

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