JS 闭包的几个代码片段

1.function showHelp(help) { document.getElementById(‘help’).innerHTML = help;}function makeHelpCallback(help) { return function() { showHelp(help); };} function setupHelp() { var helpText = [ {‘id’: ’email’, ‘help’: ‘Your e-mail address’}, {‘id’: ’name’, ‘help’: ‘Your full name’}, {‘id’: ‘age’, ‘help’: ‘Your age (you must be over 16)’} ]; for (var i = 0; i < helpText.length; i++) { var item = helpText[i]; document.getElementById(item.id).onfocus = makeHelpCallback(item.help); }}2.var funcs = [];for (var i = 0; i < 3; i++) { // let’s create 3 functions funcs[i] = function() { // and store them in funcs console.log(“My value: " + i); // each should log its value. };}for (var j = 0; j < 3; j++) { funcsj; // and now let’s run each one to see}VSvar funcs = [];function createfunc(i) { return function() { console.log(“My value: " + i); };}for (var i = 0; i < 3; i++) { funcs[i] = createfunc(i);}for (var j = 0; j < 3; j++) { funcsj; // and now let’s run each one to see}