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Last Updated : 31 Mar, 2023
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The asynchronous function can be written in Node.js using ‘async’ preceding the function name. The asynchronous function returns an implicit Promise as a result. The async function helps to write promise-based code asynchronously via the event loop. Async functions will always return a value. Await function can be used inside the asynchronous function to wait for the promise. This forces the code to wait until the promise returns a result.
Install async from npm in Node.js using the following command:
npm i async
Use async inside your Node.js project using require() method.
Example 1: Create an asynchronous function to calculate the square of a number inside Node.js.
- Create a project folder.
- Use the following command to initialize the package.json file inside the project folder.
npm init -y
- Install async using the following command:
npm i async
- Create a server.js file & write the following code inside it.
- Run the code using the below command
npm start
javascript
const async = require("async");functionsquare(x) {returnnewPromise((resolve) => {setTimeout(() => {resolve(Math.pow(x, 2));}, 2000);});}asyncfunctionoutput(x) {See AlsoUnderstanding Async/Await in Node.js | Postman BlogHow to Use Asynchronous Require Function in Node.jsHow to use an ES6 import in Node.js? - GeeksforGeeksW3Schools.comconst ans = square(x);console.log(ans);}output(10);const async = require("async");functionsquare(x) {returnnewPromise((resolve) => {setTimeout(() => {resolve(Math.pow(x, 2));}, 2000);});}asyncfunctionoutput(x) {const ans = await square(x);console.log(ans);}output(10);Output:
Example 2: Create an asynchronous function to calculate the sum of two numbers inside Node.js using await. Perform the above procedure to create a Node.js project.
javascript
const async = require("async");functionsquare(a, b) {returnnewPromise(resolve => {setTimeout(() => {resolve(a + b);}, 2000);});}asyncfunctionoutput(a, b) {const ans = await square(a, b);console.log(ans);}output(10, 20);Output:
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'); $('.spinner-loading-overlay').show(); jQuery.ajax({ url: writeApiUrl + 'create-improvement-post/?v=1', type: "POST", contentType: 'application/json; charset=utf-8', dataType: 'json', xhrFields: { withCredentials: true }, data: JSON.stringify({ gfg_id: post_id, check: true }), success:function(result) { jQuery.ajax({ url: writeApiUrl + 'suggestions/auth/' + `${post_id}/`, type: "GET", dataType: 'json', xhrFields: { withCredentials: true }, success: function (result) { $('.spinner-loading-overlay:eq(0)').remove(); var commentArray = result; if(commentArray === null || commentArray.length === 0) { // when no reason is availaible then user will redirected directly make the improvment. // call to api create-improvement-post $('body').append('
'); $('.spinner-loading-overlay').show(); jQuery.ajax({ url: writeApiUrl + 'create-improvement-post/?v=1', type: "POST", contentType: 'application/json; charset=utf-8', dataType: 'json', xhrFields: { withCredentials: true }, data: JSON.stringify({ gfg_id: post_id, }), success:function(result) { $('.spinner-loading-overlay:eq(0)').remove(); $('.improve-modal--overlay').hide(); $('.unlocked-status--improve-modal-content').css("display","none"); $('.create-improvement-redirection-to-write').attr('href',writeUrl + 'improve-post/' + `${result.id}` + '/', '_blank'); $('.create-improvement-redirection-to-write')[0].click(); }, error:function(e) { $('.spinner-loading-overlay:eq(0)').remove(); var result = e.responseJSON; if(result.detail.non_field_errors.length){ $('.improve-modal--improve-content .improve-modal--improve-content-modified').text(`${result.detail.non_field_errors}.`); jQuery('.improve-modal--overlay').show(); jQuery('.improve-modal--improvement').show(); $('.locked-status--impove-modal').css("display","block"); $('.unlocked-status--improve-modal-content').css("display","none"); $('.improve-modal--improvement').attr("status","locked"); $('.improvement-reason-modal').hide(); } }, }); return; } var improvement_reason_html = ""; for(var comment of commentArray) { // loop creating improvement reason list markup var comment_id = comment['id']; var comment_text = comment['suggestion']; improvement_reason_html += `
${comment_text}
`; } $('.improvement-reasons_wrapper').html(improvement_reason_html); $('.improvement-bottom-btn').html("Create Improvement"); $('.improve-modal--improvement').hide(); $('.improvement-reason-modal').show(); }, error: function(e){ $('.spinner-loading-overlay:eq(0)').remove(); // stop loader when ajax failed; }, }); }, error:function(e) { $('.spinner-loading-overlay:eq(0)').remove(); var result = e.responseJSON; if(result.detail.non_field_errors.length){ $('.improve-modal--improve-content .improve-modal--improve-content-modified').text(`${result.detail.non_field_errors}.`); jQuery('.improve-modal--overlay').show(); jQuery('.improve-modal--improvement').show(); $('.locked-status--impove-modal').css("display","block"); $('.unlocked-status--improve-modal-content').css("display","none"); $('.improve-modal--improvement').attr("status","locked"); $('.improvement-reason-modal').hide(); } }, }); } else { if(loginData && !loginData.isLoggedIn) { $('.improve-modal--overlay').hide(); if ($('.header-main__wrapper').find('.header-main__signup.login-modal-btn').length) { $('.header-main__wrapper').find('.header-main__signup.login-modal-btn').click(); } return; } } }); $('.left-arrow-icon_wrapper').on('click',function(){ if($('.improve-modal--suggestion').is(":visible")) $('.improve-modal--suggestion').hide(); else{ $('.improvement-reason-modal').hide(); } $('.improve-modal--improvement').show(); }); function loadScript(src, callback) { var script = document.createElement('script'); script.src = src; script.onload = callback; document.head.appendChild(script); } function suggestionCall() { var suggest_val = $.trim($("#suggestion-section-textarea").val()); var array_String= suggest_val.split(" ") var gCaptchaToken = $("#g-recaptcha-response-suggestion-form").val(); var error_msg = false; if(suggest_val != "" && array_String.length >=4){ if(suggest_val.length <= 2000){ var payload = { "gfg_post_id" : `${post_id}`, "suggestion" : `
${suggest_val}
`, } if(!loginData || !loginData.isLoggedIn) // User is not logged in payload["g-recaptcha-token"] = gCaptchaToken jQuery.ajax({ type:'post', url: "https://apiwrite.geeksforgeeks.org/suggestions/auth/create/", xhrFields: { withCredentials: true }, crossDomain: true, contentType:'application/json', data: JSON.stringify(payload), success:function(data) { jQuery('.spinner-loading-overlay:eq(0)').remove(); jQuery('#suggestion-section-textarea').val(""); jQuery('.suggest-bottom-btn').css("display","none"); // Update the modal content const modalSection = document.querySelector('.suggestion-modal-section'); modalSection.innerHTML = `
Thank You!
Your suggestions are valuable to us.
You can now also contribute to the GeeksforGeeks community by creating improvement and help your fellow geeks.
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