splice

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: This question already has an answer here: How do you clone an Array of Objects in Javascript? 29 answers using splice(0) to duplicate arrays 3 answers In this plunk I have an example of an array of objects a that I copy with slice() to b . I alter one of the objects in a but it changes also b . Isn't slice supposed to copy the array, including its contents? I need a and b to have different pointers. Javascript var a = [{x1:1, x2:2}, {x1:3, x2:4}]; var b = a.slice(); a[1].x1 = 5; console.log(b[1]); this prints: x1: 5 x2: 4 回答1: From MDN: For

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am currently using the Chrome console to do some debugging for a Greasemonkey script. From the console I run var opp = document.querySelectorAll('a[class="F-reset"]'); and it works as expected. But if I try to remove the first element with opp.splice(0,1) I get the following error Uncaught TypeError: opp.splice is not a function at <anonymous>:2:5 at Object.InjectedScript._evaluateOn (<anonymous>:905:140) at Object.InjectedScript._evaluateAndWrap (<anonymous>:838:34) at Object.InjectedScript.evaluate (<anonymous>:694:21) If I try to run

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have a small issue with understanding why I'm getting this output. var arr = ["a", "b", "c", "d", "e", "f"]; arr.splice(2,0,"1"); console.log(arr); var arr2 = ["a", "b", "c", "d", "e", "f"]; arr2 = arr2.splice(2,0,"2"); console.log(arr2); ouput is: [ 'a', 'b', '1', 'c', 'd', 'e', 'f' ] [] Why is the second line of output not: [ 'a', 'b', '2', 'c', 'd', 'e', 'f' ] Is it an issue of assignment or what? 回答1: Reading about splice method. It returns An array containing the removed elements. If only one element is removed, an array of one

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: If you have an array as part of your state, and that array contains objects, whats an easy way to update the state with a change to one of those objects? Example, modified from the tutorial on react: var CommentBox = React.createClass({ getInitialState: function() { return {data: [ { id: 1, author: "john", text: "foo" }, { id: 2, author: "bob", text: "bar" } ]}; }, handleCommentEdit: function(id, text) { var existingComment = this.state.data.filter({ function(c) { c.id == id; }).first(); var updatedComments = ??; // not sure how to do this

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Is there any simpler way to swap two elements in an array? var a = list[x], b = list[y]; list[y] = a; list[x] = b; 回答1: You only need one temporary variable. var b = list[y]; list[y] = list[x]; list[x] = b; 回答2: If you want a single expression, using native javascript, remember that the return value from a splice operation contains the element(s) that was removed. var A = [1, 2, 3, 4, 5, 6, 7, 8, 9], x= 0, y= 1; A[x] = A.splice(y, 1, A[x])[0]; alert(A); // alerts "2,1,3,4,5,6,7,8,9" Edit: The [0] is necessary at the end of the expression as

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: var arr = [ 1 , 2 , 3 , 5 , 6 ]; I want to remove the 1st element of the array so that it becomes: var arr = [ 2 , 3 , 5 , 6 ]; To extend this question, what if I want to remove the 2nd element of the array so that it becomes: var arr = [ 1 , 3 , 5 , 6 ]; 回答1: For a more flexible solution, use the splice() function. It allows you to remove any item in an Array based on Index Value: var indexToRemove = 0 ; var numberToRemove = 1 ; arr . splice ( indexToRemove , numberToRemove ); 回答2: shift() is ideal for your situation. shift()

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Possible Duplicates: How to unset a Javascript variable? How to remove a property from a javascript object I'm looking for a way to remove/unset the properties of a JS object so they'll no longer come up if I loop through the object doing for (var i in myObject) . How can this be done? 回答1: simply use delete , but be aware that you should read fully what the effects are of using this: delete object.index; //true object.index; //undefined but if I was to use like so: var x = 1; //1 delete x; //false x; //1 but if you do wish to delete

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: Following a prior post on how to update the order of an array. I followed the suggestion of Michael Best and used splice() to modify the ordering of my array on button click self . moveup = function ( itemIndex ) { var i = self . itemList . indexOf ( itemIndex ); if ( i >= 1 ){ var array = self . itemList (); self . itemList . splice ( i - 1 , 2 , array [ i ], array [ i - 1 ]); } Where I am having trouble is in incrementing the items in the array. From reading the usage of Array Splice The first param indicates where the change

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am trying to remove certain values from an array containing input fields in a form: allFields = theForm.getElementsByTagName("INPUT"); for(j = 0; j < allFields.length; j++) { if(allFields[j].className == "btn" || allFields[j].className == "lnk") { allFields.splice(j,1); } } It causes an error. Firebug shows following error and the script doesn't work. allFields.splice is not a function This also happened with any other Array method I tried. How can I fix this? 回答1: allFields is not an array, but a NodeList . If you want to remove elements,

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I'm trying to build a web-page for which I need to shovel around several 100MB of data in JavaScript. With different browsers I run into "maximum call stack size exceeded" errors at different data amounts. Can I fix this issue by going through my code and trying to move local variables inside functions into a more global scope to try to get them to be allocated on the heap instead of the stack? Or do these concepts not exist in JavaScript? (As far as I know, I don't have any major recursive loops in my data, so it really is a couple of huge